# data[].attributes.headline
April 8, 2024 We will experience a partial eclipse in our region.

# data[].attributes.subject
April 8, 2024 We will experience a partial eclipse in our region.

# data[].attributes.attachment_link.readable_text
Carte des circonstances locales de l'éclipse

Pour connaître les heures exactes d'un endroit donné, nous recommandons l'utilisation de cette carte interactive de Xavier Jubier, qui vous permet de cliquer sur votre localité. Attention, les heures sont en temps universel. Soustraire 5 heures pour obtenir l'heure normale de l'Est (HNE), ou 4 heures pour obtenir l'heure avancée (HAE). L'éclipse du 8 avril prochain se produira à l'heure avancée. Notez qu'un bouton dans l'interface permet d'afficher l'heure locale.

.

Tableau des heures pour quelques villes dans la bande de totalité

Tableau des heures pour quelques villes à l'extérieur de la bande de totalité (éclipse partielle seulement)

# data[].attributes.attachment_link.title
Observing Eclipses - Where to Observe Eclipses

# data[].attributes.attachment_link.description
Find out where to observe the different eclipses in Quebec with our interactive geolocation map.

# data[].attributes.headline
Everything you need to know about a solar eclipse!

# data[].attributes.subject
Everything you need to know about a solar eclipse!

# data[].attributes.body
https://letstalkscience.ca/educational-resources/backgrounders/get-ready-a-total-solar-eclipse

# data[].attributes.headline
Québec Science: Tout ce que vous devez savoir sur l’éclipse solaire totale du 8 avril 2024

# data[].attributes.subject
Québec Science: Tout ce que vous devez savoir sur l’éclipse solaire totale du 8 avril 2024

# data[].attributes.body
REMEMBER: YOU CANNOT LOOK DIRECTLY AT THE SUN AS THIS IS HARMFUL TO YOUR EYES!

https://letstalkscience.ca/educational-resources/hands-on-activities/three-ways-make-a-solar-eclipse-viewer

# data[].attributes.attachment_link.description
On April 8, 2024, part of Canada will observe a total solar eclipse. When the Moon aligns perfectly between Earth and the Sun, many spectators will be plunged into temporary darkness.

# data[].attributes.headline
Québec Science : Comment observer l’éclipse en toute sécurité?

# data[].attributes.subject
Québec Science : Comment observer l’éclipse en toute sécurité?

# data[].attributes.attachment_link.readable_text
À l'exception de la brève phase de l'éclipse où le Soleil sera entièrement caché, des lunettes ayant un filtre conforme à la norme ISO 12312-2 sont nécessaires pour protéger les yeux. Il ne faut pas utiliser de simples lunettes de soleil pour observer l'événement astronomique.

Même si le Soleil est presque entièrement caché, les lunettes d'éclipse sont nécessaires pour observer directement le phénomène. " Pendant l'éclipse, la Lune vient cacher de plus en plus la surface du Soleil. À partir d'un certain seuil, la luminosité totale a suffisamment diminué pour désactiver notre réflexe d'éblouissement. Mais la partie restante est aussi brillante et peut causer des dommages à la rétine de l'œil ", avertit Marc Jobin, astrophysicien au Planétarium de Montréal.

Lorsque vous n'observez pas l'éclipse - vous êtes en train de vous déplacer ou de faire vos tâches habituelles à l'extérieur - il n'est pas nécessaire de porter de protection oculaire.

Des méthodes d'observation indirectes peuvent également être utilisées. Kelly Korreck, responsable du programme de la NASA pour les éclipses solaires de 2023 et de 2024, propose celle-ci : " Tournez le dos au soleil et utilisez vos mains pour créer de petits trous en croisant vos doigts. La lumière traversera ces trous pour projeter l'éclipse au sol ", nous explique-t-elle. Une passoire ou une râpe à fromage pourraient aussi faire l'affaire! Voir d'autres exemples.

# data[].attributes.attachment_link.title
Comment observer l'éclipse en toute sécurité? - Québec Science

# data[].attributes.attachment_link.description
Il existe plusieurs moyens sécuritaires de suivre l'éclipse solaire sans mettre en danger sa rétine. Petit guide!

# data[].attributes.headline
Québec Science : « Une éclipse solaire est un événement à admirer, pas à craindre »

# data[].attributes.subject
Québec Science : « Une éclipse solaire est un événement à admirer, pas à craindre »

# data[].attributes.attachment_link.readable_text
RC La lésion se produit sans douleur car la rétine n'a pas de capteurs de douleur. La perte réelle de fonction qui en résulte se produit environ 12 heures plus tard. En général, le lendemain de l'éclipse solaire, la victime remarque qu'elle voit mal les détails de son visage dans le miroir de la salle de bain, ou qu'elle ne peut pas lire le journal, etc.

En cas d'exposition juste au-dessus de la dose seuil, les dommages sont réversibles, mais seulement après plusieurs semaines ou mois. D'après les statistiques sur les lésions oculaires liées aux éclipses solaires accumulées au fil des ans, plus de 50 % des personnes touchées finissent par recouvrer la vue. Toutefois, les autres peuvent garder une vision plus ou moins réduite une fois la rétine guérie.
QS Lors des éclipses totales précédentes, comme celle de 2017 aux États-Unis, vous avez recensé des lésions oculaires chez environ 100 personnes sur 215 millions d'observateurs et observatrices. Est-ce exact?
RC Oui, c'est notre meilleure estimation. Elle est basée sur les rapports reçus par divers groupes de professionnels des soins oculaires dans les semaines et les mois qui ont suivi cette éclipse. J'ai personnellement reçu quelques rapports de lésions oculaires, mais les professionnels consultés les ont toutes jugées mineures. Et, pour autant que je me souvienne, aucun de ces patients n'a eu de séquelles permanentes.
QS Vous avez observé près de 30 éclipses. Que pensez-vous de la frilosité des centres scolaires et des autorités ?
RC Je pense que les autorités scolaires de l'Ontario et du Québec tentent d'échapper à leurs responsabilités. Bien que Discover the Universe Canada et plusieurs départements universitaires d'astronomie aient essayé d'informer les élèves et de leur procurer des lunettes sûres, les autorités continuent d'empêcher les écoles de fournir du matériel ou une supervision pour regarder l'éclipse solaire en toute sécurité.

L'éclipse du 8 avril sera ma 30 e éclipse solaire et ma 20 e éclipse totale ! Je trouve regrettable que les gouvernements évitent de saisir l'occasion de cet événement, l'un des plus spectaculaires de la nature, pour mieux faire comprendre au public la science, la méthode scientifique et la beauté de ce phénomène. Une éclipse solaire est un événement à admirer, pas à craindre.

# data[].attributes.attachment_link.title
" Une éclipse solaire est un événement à admirer, pas à craindre " - Québec Science

# data[].attributes.attachment_link.description
Après plusieurs jours d'hésitation, la nouvelle est tombée : en raison de l'éclipse solaire totale, la journée du 8 avril sera une journée pédagogique à Montréal. Quels sont les risques réels de s'endommager les yeux? Entrevue avec le Dr Ralph Chou, spécialiste de la question.

# data[].attributes.attachment_link.readable_text
8 avril 2024

Éclipse totale de Soleil

Plusieurs millions de Québécois.e.s habitent la bande de totalité et ont pu observer ce phénomène astronomique rare, qui n'arrive généralement qu'une fois dans une vie.

Une éclipse totale de Soleil a eu lieu le 8 avril 2024 en après-midi et fut visible dans le sud du Québec.

Ce phénomène astronomique unique et rare se produit lorsque la Lune se place entre la Terre et le Soleil et le cache complètement pour une courte période de temps.

Cette éclipse est un événement unique pour le Québec; ce sera la première éclipse totale depuis 1972 et la dernière importante du siècle dans le sud de la province.

Une éclipse totale de Soleil a eu lieu le 8 avril 2024 en après-midi dans le sud du Québec.

Ce phénomène astronomique unique et rare se produit lorsque la Lune se place entre la Terre et le Soleil et le cache complètement pour une courte période de temps.

Cette éclipse est un événement unique pour le Québec; ce sera la première éclipse totale depuis 1972 et la dernière importante du siècle dans le sud de la province.

Où l'observer

La région où l'éclipse est totale (la bande de totalité) traverse le sud du Québec, notamment la grande région de Montréal, la Montérégie et l'Estrie.

Au centre de cette région se trouve le mont Mégantic, haut lieu de l'astronomie québécoise, où la totalité (période pendant laquelle la Lune cache parfaitement le Soleil) fut la plus longue, soit environ 3 minutes 30 secondes.

Ce site est une collaboration d'institutions impliquées dans la recherche et l'éducation scientifique au Québec et spécialisées en astronomie. Il est le point d'information central pour le phénomène du 8 avril 2024 et sera mis à jour au cours du temps.

Comment observer en sécurité

Attention aux dangers potentiels : regarder le Soleil pendant une éclipse (ou à tout autre moment) peut causer des dommages temporaires ou permanents à la rétine.

Équipez-vous de filtres spécialement conçus à cet effet pour observer l'éclipse de manière sécuritaire. Ces filtres bloquent plus de 99,9 % des rayons du Soleil.

Consultez le lien suivant pour les lieux de vente ou de distribution de lunettes à éclipse.

# data[].attributes.attachment_link.description
Une éclipse totale de Soleil aura lieu le 8 avril 2024 en après-midi et sera visible dans le sud du Québec.

# data[].attributes.attachment_link.readable_text
April 8, 2024

Total eclipse of the Sun
Several million Quebecers live in the band of totality and will be able to observe this rare astronomical phenomenon, which usually happens only once in a lifetime. See the April 4, 2023, Media Release

A total solar eclipse will take place on the afternoon of April 8, 2024 and will be visible in southern Quebec.

This unique and rare astronomical phenomenon occurs when the Moon is placed between the Earth and the Sun and completely hides it for a short period of time.

This eclipse is a unique event for Quebec; it will be the first total eclipse since 1972 and the last major one of the century in the province.

Where to observe it

The region where the eclipse will be total (the strip of totality) crosses southern Quebec, including the greater Montreal area, Montérégie and the Eastern Townships.

At the centre of this region is Mont Mégantic, the heart of Quebec astronomy, where the totality (period during which the Moon perfectly hides the Sun) will be the longest, about 3 minutes and 30 seconds. View map of totality

Stay tuned for details on specific locations where it will be possible to observe.

This site is a collaboration of institutions involved in research and scientific education in Quebec and specialized in astronomy. It will be the focal point for the April 8, 2024 phenomenon and will be updated in the fall of 2023.

Be aware of the potential dangers: looking at the Sun during an eclipse (or at any other time) can cause temporary or permanent damage to the retina.

Equip yourself with specially designed filters to safely view the eclipse. These filters block over 99.9% of the Sun's rays.

Details will come on where to buy or distribute eclipse glasses.

# data[].attributes.attachment_link.description
A total solar eclipse will take place on the afternoon of April 8, 2024 and will be visible in southern Quebec.

# data[].attributes.attachment_link.description
L’éclipse du 8 avril 2024 sera totale au Mexique, aux États-Unis et au Canada.

# data[].attributes.headline
Espace pour la vie (Planétorium) in english

# data[].attributes.subject
Espace pour la vie (Planétorium) in english

# data[].attributes.attachment_link.readable_text
Il ne faut pas regarder le Soleil directement sans Très important! protection adéquate. Sinon, cela peut entraîner de graves problèmes, jusqu'à la perte partielle ou totale de la vue.

Les éclipses sont des merveilles de la nature. Bien qu'elles soient assez fréquentes, les occasions d'admirer des éclipses sont assez rares. En effet, il y a quatre à sept éclipses solaire ou lunaire par année, mais elles ne sont visibles que pour les gens qui se trouvent dans la bande d'ombre de l'éclipse.

Qu'est-ce qu'une éclipse?

Une éclipse survient lorsque la lumière d'un corps céleste ( p. ex. le Soleil, la Lune, les planètes) est temporairement obstruée par un autre corps céleste. Les éclipses n'ont pas seulement lieu sur Terre : ce phénomène survient aussi sur d'autres planètes, comme Jupiter ou Neptune.

Qu'est-ce qu'une éclipse solaire?

Une éclipse solaire se produit lorsque la Lune passe entre la Terre et le Soleil et projette son ombre sur la Terre.

Cette animation montre le déroulement partiel de l'éclipse solaire du , avec la Lune qui cache le Soleil et son ombre qui tombe sur la Terre. Animation créée avec WorldWide Telescope. (Sources : Agence spatiale canadienne, WorldWide Telescope.)

Dans les endroits qui se trouvent dans la trajectoire de l'ombre de la Lune, on a l'impression que le Soleil s'est assombri. Selon la distance entre le Soleil et la Lune et leur position, il est possible de voir trois types d'éclipses solaires :

Éclipse totale : La Lune recouvre complètement le Soleil.

Éclipse annulaire : La Lune se trouve plus près du Soleil. Ainsi, la Lune semble plus petite que le Soleil de notre point de vue. Un anneau du Soleil est visible autour de la Lune.

Éclipse partielle : Le Soleil et la Lune ne sont pas parfaitement alignés. Seulement une partie du Soleil est cachée par la Lune.

Quand sera la prochaine éclipse solaire totale visible au Canada?

La prochaine éclipse du Soleil totale sera visible au Canada le . La bande d'ombre du maximum de l'éclipse balaiera alors le Mexique, les États-Unis et l'est du Canada.

L'éclipse solaire partielle du

Le , une éclipse solaire partielle sera visible dans l'Est canadien.

Éclipse solaire annulaire. (Source : ASC.)

Comment observer une éclipse solaire en toute sécurité

Lors d'une éclipse solaire, il est primordial de porter des lunettes filtrantes conçues pour l'observation d'éclipses (norme internationale ISO 12312-2). De simples lunettes de soleil ne conviennent absolument pas : elles ne protègent pas convenablement les yeux pour ce type d'observation.

Lors d'une éclipse solaire totale, la bande d'ombre projetée au maximum de l'éclipse fait environ 110 à 115 kilomètres de largeur, où le Soleil est complètement couvert par la Lune pour une courte période (entre deux et trois minutes). Il s'agit du moment le plus spectaculaire puisque les personnes assez chanceuses pour se trouver dans cette bande d'ombre lorsque l'éclipse est totale peuvent voir la couronne solaire, la chromosphère, des protubérances solaires et des jets coronaux. Il est très important de prendre des mesures de sécurité pour bien se protéger les yeux avant et après la phase où l'éclipse solaire est totale.

Pour ceux qui se trouvent à l'extérieur de la bande d'ombre, le Soleil est partiellement couvert par la Lune (éclipse partielle). Lors d'une éclipse solaire partielle, une protection des yeux est de mise en tout temps.

Si vous n'avez pas de lunettes filtrantes conçues pour l'observation d'éclipses, il existe d'autres façons de les observer, par exemple en utilisant une boîte à éclipse solaire que vous pouvez facilement fabriquer vous-même.

Poursuivez l'exploration

Date de modification :

# data[].attributes.attachment_link.description
Découvrez les causes des éclipses solaires et la meilleure façon de les observer en toute sécurité.

# data[].attributes.attachment_link.readable_text
Looking directly at the Sun, without Very important! appropriate protection, can lead to serious problems such as partial or complete loss of eyesight.

An eclipse is a wonder to behold. Although eclipses occur more often than you might think, there aren't many opportunities to admire them. There are four to seven solar or lunar eclipses per year, but only those people along the path of an eclipse are able to see it.

What is an eclipse?

An eclipse occurs when the light of a body outside Earth's atmosphere (Sun, Moon, planets, etc.) is temporarily blocked by another body. Eclipses don't just happen on Earth: they also take place on other planets, like Jupiter and Neptune.

What is a solar eclipse?

A solar eclipse occurs when the Moon comes between the Earth and the Sun, casting a shadow on Earth.

This animation partially shows the solar eclipse on , with the Moon hiding the Sun and casting its shadow on Earth. Animation created with WorldWide Telescope. (Credits: Canadian Space Agency, WorldWide Telescope)

From the locations along the Moon's umbra trajectory, it appears as if the Sun has gone dark. Depending on the distance between the Sun and the Moon and their positions, it is possible to see three kinds of solar eclipses:

Total eclipse: the Moon completely covers the Sun

Annular eclipse: the Moon is closer to the Sun; hence the Moon appears smaller than the Sun. A ring of light from the Sun is always visible

Partial eclipse: the Sun and the Moon are not perfectly aligned, so only a part of the Sun is hidden by the Moon

When will the next total solar eclipse be visible in Canada?

The next total solar eclipse to be visible in Canada will occur on , when the path of totality will cross Mexico, the United States and eastern Canada.

Partial solar eclipse of

On , a partial solar eclipse will be visible in Eastern Canada.

Annular solar eclipse. (Credit: CSA)

How to safely watch a solar eclipse

During any solar eclipse, it is imperative to wear special glasses with filters designed for eclipse watching (ISO 12312-2 international standard) to prevent eye damage. Regular sunglasses will not protect your eyes sufficiently.

During a total solar eclipse, the path of totality is a narrow corridor approximately 100 to 115 km wide where the Sun appears to be completely covered by the Moon for a short period of time (between 2 and 3 minutes). This is the most spectacular part of the eclipse, as those who are lucky enough to be in this corridor are able to see the Sun's corona, the chromosphere, prominences and streamers. Proper eye protection is essential before and after totality.

For those outside the path of totality, the Sun appears to be partially covered by the Moon (partial eclipse). When watching a partial solar eclipse, proper eye protection is required at all times.

If you don't have special glasses designed for eclipse watching, there are other ways to watch an eclipse, such as an eclipse projector, which you can easily learn how to make.

Explore further

Date modified:

# data[].attributes.attachment_link.title
Solar eclipses guide: when is the next solar eclipse?

# data[].attributes.attachment_link.description
Discover what causes solar eclipses and how you can observe them safely.

# data[].attributes.attachment_link.readable_text
On April 8, 2024, a total solar eclipse will cross North America, passing over Mexico, the United States, and Canada. A total solar eclipse happens when the Moon passes between the Sun and Earth, completely blocking the face of the Sun. The sky will darken as if it were dawn or dusk.

Safety is the number one priority when viewing a total solar eclipse. Be sure you're familiar with when you need to wear specialized eye protection designed for solar viewing by reviewing these safety guidelines.

2024 Total Solar Eclipse: Through the Eyes of NASA

Watch live with us as a total solar eclipse moves across North America on April 8, 2024, traveling through Mexico, across the United States from Texas to Maine, and out across Canada's Atlantic coast.

To see NASA's broadcast in Spanish, a live stream of sounding rocket launches during the eclipse, and more, click below.
Experience the Eclipse

Total Solar Eclipse Broadcast

Safety

Except during the brief total phase of a total solar eclipse, when the Moon completely blocks the Sun's bright face, it is not safe to look directly at the Sun without specialized eye protection for solar viewing.

Viewing any part of the bright Sun through a camera lens, binoculars, or a telescope without a special-purpose solar filter secured over the front of the optics will instantly cause severe eye injury.

When watching the partial phases of the solar eclipse directly with your eyes, which happens before and after totality, you must look through safe solar viewing glasses ("eclipse glasses") or a safe handheld solar viewer at all times. You can also use an indirect viewing method, such as a pinhole projector.​

What to Expect

The April 8, 2024, eclipse will be a total solar eclipse. It will be the last total solar eclipse visible from the contiguous United States until 2044.

A total solar eclipse happens when the Moon passes between the Sun and Earth, completely blocking the face of the Sun. People viewing the eclipse from locations where the Moon's shadow completely covers the Sun - known as the path of totality - will experience a total solar eclipse. The sky will darken, as if it were dawn or dusk. Weather permitting, people along the path of totality will see the Sun's corona, or outer atmosphere, which is usually obscured by the bright face of the Sun.

Where & When

The April 8, 2024, total solar eclipse will begin over the South Pacific Ocean and will cross North America, passing over Mexico, United States, and Canada.

Weather permitting, the first location in continental North America that will experience totality is Mexico's Pacific coast at around 11:07 a.m. PDT.

The path of the eclipse continues from Mexico, entering the United States in Texas, and traveling through Oklahoma, Arkansas, Missouri, Illinois, Kentucky, Indiana, Ohio, Pennsylvania, New York, Vermont, New Hampshire, and Maine. The eclipse will enter Canada in Southern Ontario, and continue through Quebec, New Brunswick, Prince Edward Island, and Nova Scotia. The eclipse will exit continental North America on the Atlantic coast of Newfoundland, Canada, at 5:16 p.m. NDT.

Contribute to NASA Science!

On April 8, 2024, participants both in and outside the eclipse path can join NASA to learn more about our Sun and Earth and the effects of a total solar eclipse.

From cell phone apps to use on April 8 to recording the sounds of the eclipse, there are opportunities for anyone to get involved with studying this celestial event.

On April 8, the Moon's shadow will sweep across the United States, as millions will view a total solar eclipse....

Discover More Topics From NASA

# data[].attributes.attachment_link.description
On April 8, 2024, a total solar eclipse will cross North America, passing over Mexico, the United States, and Canada. A total solar eclipse happens when the Moon passes between the Sun and Earth, completely blocking the face of the Sun. The sky will darken as if it were dawn or dusk.

# data[].attributes.attachment_link.readable_text
Si vous n'avez pas eu le temps d'assister à nos formations Éclipse, vous pouvez désormais le faire selon votre propre horaire. Regardez les vidéos ci-dessous pour acquérir les connaissances dont vous avez besoin pour rester en sécurité et sensibiliser les jeunes à ce phénomène étonnant!

Éclipse 101

Éclipse 201

À l'approche de l'éclipse, vous vous demandez peut-être ce que vous pouvez faire pour vous préparer et préparer vos élèves. La première chose à faire est de vous procurer des lunettes à éclipse. Ces lunettes vous permettent d'observer en toute sécurité toutes les étapes de l'éclipse, et vous devez vous les procurer rapidement! Pour en savoir plus sur les lunettes à éclipse et les mesures de sécurité à prendre pour l'éclipse, allez voir la section suivante. Nous proposons également des formations régulières ! Vous pouvez vous inscrire à nos sessions Éclipse 101 ou 201 ici .

Une autre priorité dans la préparation est de s'informer sur les éclipses, la sécurité oculaire et les activités que vous pouvez faire pour profiter de l'éclipse avec vos élèves. À la découverte de l'univers et d'autres organisations proposent de nombreux documents, ateliers et formations pertinentes et importantes avant le grand jour. Plus à venir!

par Laurie Rousseau-Nepton

Lors d'une éclipse, même si une partie de la lumière du Soleil est bloquée par la Lune, la lumière restante peut encore endommager les yeux non protégés. Pour cette raison, il est important de se munir de lunettes à éclipse afin de pouvoir regarder directement et en toute sécurité toutes les phases partielles de l'éclipse. Ne vous laissez pas tromper par le fait que le Soleil est en grande partie couvert par la Lune; tant qu'une infime partie du Soleil est visible, vous devez utiliser des filtres solaires pour protéger vos yeux. Lorsque l'éclipse est partielle: portez vos lunettes!

Le seul moment où il est permis d'enlever ses lunettes à éclipse est pendant la totalité de l'éclipse. Pendant ces quelques minutes, la surface du Soleil est complètement bloquée par la Lune et la couronne peut être observée sans danger. En fait, si vous gardez vos lunettes pendant la totalité, vous manquerez la meilleure partie de l'éclipse puisque vous ne verrez rien! Assurez-vous de remettre vos lunettes dès que le Soleil réapparaît de derrière la Lune.

La Fédération des astronomes amateurs du Québec, Ève Christian et Farah Alibay vous expliquent comment observer l'éclipse en toute sécurité!

Il est possible d'observer une éclipse de façon indirecte: il suffit d'utiliser un objet avec un trou et de le placer au Soleil. La lumière du Soleil passe alors à travers le trou et forme l'image du Soleil sur un écran placé derrière. Lors de l'éclipse, la forme du Soleil n'est plus un cercle parfait et on peut voir la progression de l'éclipse partielle au fur et à mesure que la Lune le couvre. Il est complètement sécuritaire d'observer l'éclipse de cette façon, puisqu'on ne regarde pas le Soleil, mais bien une projection de son image sur l'écran. Ne pas observer le Soleil directement à travers le trou!

Soyez créatif et créez vos propres motifs dans un carton, ou utilisez des ustensiles de cuisine! Jetez un coup d'œil à notre activité Observation indirecte de l'éclipse pour plus d'information et d'idées.

# data[].attributes.attachment_link.title
Éclipse 2024 | À la découverte de l'univers

# data[].attributes.attachment_link.description
Pour la première fois depuis des décennies, le Québec, l'Ontario et les provinces de l'Atlantique se retrouveront sous l'ombre de la Lune le 8 avril 2024. Ici vous trouverez plus d'informations sur l'éclipse et des ressources éducatives.

# data[].attributes.attachment_link.readable_text
Total Solar Eclipse 2024

A once-in-a-lifetime event for Ontario, Quebec, and the Atlantic provinces!

For the first time in decades, Eastern and Atlantic Canada will find themselves cast beneath the shadow of the Moon on April 8, 2024. As the Moon passes directly between the Earth and the Sun, it will create a total solar eclipse, completely blocking the Sun from view for a few spectacular minutes. This is truly a once-in-a-lifetime event for Ontario, Quebec, and the Atlantic provinces, as the next total solar eclipse over eastern Canada will be in 2079, and 2106 after that!

​

You can now register for our Eclipse 101 and 201 educational training, which will cover all eclipse safety and basics (101) and how to bring eclipse science activities into your classroom (201)! These training events will be repeated through February and March.

Sun, Moon, Action!
Understanding the Eclipse

What is a Total Solar Eclipse?

A solar eclipse happens when the Moon passes between the Earth and the Sun, casting its shadow on the Earth. From our perspective, this will look like the Moon is blocking out the Sun in the sky, either completely or partially, depending on the type of eclipse and where it is being observed from. Eclipses only happen occasionally since the Moon does not orbit in the exact same plane as the Earth and the Sun. Twice a year, when all three are aligned, eclipses have the possibility of occurring worldwide.

There are several types of eclipses, but the upcoming eclipse on April 8, 2024 is a total solar eclipse, meaning that at its maximum, the Moon will completely block out the Sun. Totality, when the Sun is entirely covered by the Moon at the eclipse maximum, will follow a path across North America, sweeping over several populous Canadian cities including Kingston in Ontario, Sherbrooke in Quebec, Fredericton in New Brunswick, Summerside in Prince Edward Island, and Grand Falls - Windsor in Newfoundland.

Where will you be observing the eclipse from?
Will you be in the path of totality?

What will I see on April 8, 2024?

What you see will depend on where you are! The total eclipse will be visible from a band called the path of totality. Outside this path, people will see a partial eclipse, where the Moon will not cover the Sun completely. The closer you are to the path of totality, the more of the Sun will be covered by the Moon.

From beginning to end, the eclipse will be visible for about 2 hours. You can watch the whole thing, but the eclipse maximum is the best part. At eclipse maximum, the sky will darken as the Moon blocks out the Sun's light. Depending on where you are viewing the eclipse, what happens at the maximum will vary.

Viewing through eclipse glasses, the Sun will shrink to a sliver and then vanish. Then the Moon will completely block out the light from the Sun. During totality -and only during totality- it is safe to remove your eclipse glasses.

You'll see a dark circle in the sky (the Moon), with streaks of light coming from it. Those streaks are the Sun's corona: the faint outer layer of its atmosphere. This sight is unique to total solar eclipses! Totality will only last a few minutes, after which you will need to put on your eclipse glasses again to view the rest. The eclipse will then progress back into partial phases until it's conclusion.

Outside the path of totality

If you are not viewing the eclipse in the path of totality, your eclipse maximum will be a partial eclipse. The sky will darken as the Moon blocks out most of the light from the Sun, but there will always be a sliver of the Sun still visible.

Viewing this maximum partial phase, the Sun will be a thin crescent that shrinks in size as maximum approaches and grows in size again after. Eclipse glasses are required for viewing all phases of the eclipse outside the path of totality, including the maximum.

Depending on your location, the eclipse will start, reach maximum, and end at different times. Check the table for your viewing location:

How can I prepare for the eclipse with my students or group?

As the eclipse approaches, you may be wondering what you can do to prepare yourself and your peers. The first thing you will want to do is get eclipse glasses. These glasses enable you to safely observe all stages of the eclipse, and you will want to get them soon! You can read more about eclipse glasses and safety precautions for the eclipse in the next section. We are offering regular training sessions, too! You can register for our Eclipse 101 or 201 sessions here .

Another priority in preparation for the eclipse is to educate yourself on eclipses, eye safety, and activities you can do to enjoy the eclipse with your peers. Discover the Universe and other organizations have many relevant and important documents, workshops, and training leading up to the big day.

Workshops and Training

In this section, learn about Indigenous Knowledge on solar eclipses! Start with the video below.

We are thrilled to provide three stories from this video as written texts in English, French, Mohawk, Innu, and MikMaq. Perfect for the classrooms! Total Eclipse Story , by Samantha Doxtator, The Hiawatha Wampum and a Solar Eclipse , by Melanie Demers and Innu Story of the Eclipse by Laurie Rousseau-Nepton. Click the icon below to read it in your language of choice.

The Hiawatha Wampum and a Solar Eclipse

Innu Story of the Eclipse

Below you'll find translations of our Eclipse One-Pager in four Indigenous languages: Mohawk, Eastern Ojibway, Malecite- Passamaquoddy, and Mikmaq.

How can we observe the eclipse safely?

Looking at the Sun without proper eye protection, including during an eclipse, can severely hurt your eyesight and even damage it permanently. ​​ It is always dangerous to observe the Sun, but we naturally tend not to look at it on any sunny day. During an eclipse however, we want to look at the Sun and we need to do it safely. The easiest way to do it is to have ISO certified eclipse glasses. ​

Never look at the Sun directly with bare eyes.

Solar filters, like those in eclipse glasses and viewers, are designed to protect the eyes from the intense brightness of the Sun, blocking out most (99.997%) of the sunlight. Made from specialized materials, they block out harmful UV and IR radiation from the Sun too, only allowing a safe amount of visible light to pass through. These filters allow safe observation of the Sun. The ISO 12312-2 Standard for Solar Viewers is a policy on solar viewers and glasses that ensures the safety of the user. This specification sets requirements on specific properties of safe solar viewers, including how much visible light, UV radiation, and IR radiation reach our retinas. Only eclipse viewers and glasses that meet the ISO 12312-2 standard are guaranteed to be safe for solar viewing if they are undamaged.

During an eclipse, even though some of the sunlight is blocked by the Moon, the remaining light can still damage unprotected eyes. That is why it is important to have proper eclipse glasses or viewers so that you can safely look directly at all partial phases of the eclipse. Don't get fooled by the fact that the Sun is mostly covered by the Moon: as long as a tiny fraction of the Sun is visible, you must wear solar filters to protect your eyes. When the eclipse is partial: wear your glasses!

The only time when it is safe to remove your eclipse glasses is during totality. During these few minutes, the Sun's surface is completely blocked by the Moon and the corona is safe to look at directly. In fact, if you keep your glasses during totality, you will miss the best show since you won't see anything! Make sure to put your glasses back on as soon as the Sun reappears from behind the Moon.

Indirectly viewing the eclipse

It is possible to observe an eclipse indirectly using the pinhole method. All you have to do is use an object with a small hole in it. Sunlight then passes through the hole and forms the image of the Sun on a screen placed behind it. During the eclipse, the shape of the Sun is no longer a perfect circle and we can see the progress of the partial eclipse as the Moon covers it. It is completely safe to observe the eclipse this way, since we are not looking at the Sun, but at a projection of its image. Do not look directly at the Sun through the hole!

Be creative and create your own patterns on cardboard, or use kitchen utensils! See our activity Indirect Observation of the Eclipse for more information and ideas.

Watch this solar eclipse eye safety video with Professor Ralph Chou

How can I teach about the eclipse?

You can also register for our Eclipse 101 and 201 educational training, which will cover all eclipse safety and basics (101) and how to bring eclipse science activities into your classroom (201)! These training events will be repeated through February and March.

There are many ways to introduce the eclipse to your students. It is important to start by explaining the motions of and interactions between the Earth, the Moon, and the Sun, and what is physically happening during a solar eclipse: the Moon blocks the sunlight from reaching Earth and what we see from within the shadow of the Moon is the Moon covering the Sun in the sky. Classroom activities are a great way to teach eclipses to your students.

Activities for your classroom

Here are additional resources to introduce and teach eclipses in the classroom:

- good for all provinces!

# data[].attributes.attachment_link.description
For the first time in decades, Eastern and Atlantic Canada will find themselves cast beneath the shadow of the Moon on April 8, 2024. Find information about the total solar eclipse 2024.

# data[].attributes.attachment_link.readable_text
ERROR

Javascript isn't activated or your browser does not support Javascript

You cannot browse this web page and site correctly before activating Javascript in the browser prefs

# data[].attributes.attachment_link.title
Mexico - USA - 2024 April 8 Total Solar Eclipse - Interactive Google Map - Xavier Jubier

# data[].attributes.attachment_link.description
2024 April 8 Total Solar Eclipse in Mexico, the USA or Canada by Xavier Jubier

# data[].attributes.attachment_link.readable_text
Les élèves se préparent à observer une éclipse du Soleil à travers des activités sur les phases de la Lune, la modélisation de l'alignement de la Terre, la Lune et le Soleil et la fabrication d'un projecteur de Soleil.

Variable selon les dispositions choisies

2e cycle (propositions d'adaptation pour les 1er et 3e cycles)

Partout, mais en particulier les régions où l'éclipse sera totale: une partie de l'île de Montréal, la Montérégie, l'Estrie, le Centre-du-Québec, Chaudière-Appalaches et les Îles-de-la-Madeleine.
Vous pouvez consulter la carte du Québec avec les différentes régions : https://www.eclipsequebec.ca/carte/

Intention(s) d'apprentissage:

Comprendre les phases de la Lune, reconnaitre les astres que l'on peut observer dans le ciel et leur rôle respectif lors d'une éclipse solaire et tenir un carnet d'observations.

La terre est l'espace

Systèmes et interaction ; Système Soleil-Terre-Lune ; Illustrer les phases du cycle lunaire (pleine lune, nouvelle lune, premier et dernier quartiers)

Systèmes et interaction ; Système Soleil-Terre-Lune ; Illustrer la formation des éclipses (lunaire, solaire)

Langage approprié ; Terminologie liée à la compréhension de la Terre et de l'espace ; Utiliser adéquatement la terminologie associée à l'univers de la Terre et de l'espace

Langage approprié ; Terminologie liée à la compréhension de la Terre et de l'espace ; Distinguer le sens d'un terme utilisé dans un contexte scientifique et technologique du sens qui lui est attribué dans le langage courant.

Stratégie(s) et technique(s):

Recourir à des techniques et des outils d'observations variés.

Recourir à des outils de consignation.

· Schéma des phases de la Lune

· Fiche de prise de notes d'observation des phases de la Lune

· Modélisation avec Ballon

· Globe terrestre (ou gros ballon) pour la Terre

· Balle (par exemple balle de sécheuse) pour la Lune

· Source de lumière si activité faite à l'intérieur, mais idéalement Soleil (à l'extérieur)

· Modélisation à l'échelle

· Balle de styromousse 2,5 cm (Terre)

· Pâte à modeler (pour faire une boule de 0,7 cm de diamètre) (Lune)

· Trombones (2) ou cure-dents (2)

· Ruban adhésif ou pince à dessin (pince à clip) (2)

· Règle en bois de 1 m

· Projecteur de Soleil

· Papier cartonné ou boite de céréales recyclée.

· Feuille d'aluminium

· Ciseau

· Ruban adhésif

· Punaise

· Marqueurs ou crayon de couleur

· Carton ou feuille blanche (écran)

Avant le 8 avril

Étape 0 : Activation des connaissances (Demander aux élèves)

Phases de la Lune

· Avez-vous déjà pris le temps d'observer le ciel en journée ? Que pouvons-nous voir dans le ciel?

· Avez-vous déjà pris le temps d'observer le ciel en soirée ou la nuit? Que pouvons-nous voir dans le ciel?

· Est-ce que la Lune tourne autour de la Terre ? Est-ce que la Lune a une ombre ?

Éclipses

· Que se passe-t-il si la Terre, la Lune et le Soleil sont parfaitement alignés, avec la Lune entre la Terre et la Soleil ? Que se passe-t-il si c'est la Terre qui est entre la Lune et le Soleil ?

Étape 1 : Les phases de la Lune (démarche d'observation)

· Enseigner les phases de la Lune. Pour les élèves du 2e cycle, vous pouvez leur montrer un schéma des phases et leur apprendre les noms des phases et l'image correspondante. Au 3e cycle, vous pouvez aller plus loin en leur expliquant pourquoi nous voyons seulement une certaine partie de la moitié de la Lune qui fait face à la Terre (avec un schéma illustrant la position de la Terre, de la Lune et du Soleil)

· Sur une période d'un mois, il est intéressant de demander aux élèves de regarder la Lune à la maison et de noter leurs observations sur une fiche d'observation. Dans le cas où les observations sont impossibles, il est également possible d'utiliser l'application Stellarium. En variant les prises de notes d'observations (Observations faites par les élèves, calendrier lunaire et Stellarium), il est possible de permettre aux élèves de mettre en commun leurs observations et de discuter de la validité des résultats, par exemple. Avec l'application, il est également possible d'observer la Lune selon différents points de vue sur la Terre et ainsi aborder la question : " Est-ce que les habitants de la Terre voient tous la même chose au même moment ? "

Étape 2 : La modélisation (Démarche de modélisation)

Système Terre-Soleil-Lune

· En équipe de 3, les élèves représentent les astres. Un élève représente le Soleil, un autre la Lune, un dernier la Terre. L'enseignant demande à ces trois élèves de se déplacer les uns par rapport aux autres afin de vérifier s'ils ont bien compris comment la Terre, la Lune et le Soleil se déplacent. Il est possible d'utiliser des accessoires ou des colliers pour permettre aux élèves de s'identifier entre eux : https://www.asc-csa.gc.ca/fra/jeunes-educateurs/activites/bouge-comme-la-terre-et-la-lune.asp

· Nuance pédagogique. Selon le niveau, on peut s'assurer que les élèves aient bien compris le mouvement de révolution de la Lune autour de la Terre et sa période (un peu plus de 27 jours), le mouvement de révolution de la Terre autour du Soleil et sa période (365,25 jours), ainsi que les différents mouvements de rotation des astres sur eux-mêmes (la Terre en 24h, la Lune en un peu plus de 27 jours et le Soleil en 25 jours). De plus, c'est possible de souligner que tous ces mouvements de révolution et de rotation se déroulent dans le même sens (sens inverse des aiguilles d'une montre vue d'un point situé au-dessus des élèves).

Vous pouvez aussi faire cette activité dans une pièce sombre, en utilisant une lampe de poche (au lieu du Soleil) comme source de lumière.

Tenir la balle Lune et reste proche du globe Terre.

Aligner la Lune afin qu'elle projette une ombre sur la Terre.

Regarder attentivement l'ombre.

Questionner les élèves : par exemple. Est-ce que l'ombre couvre toute la Terre ? Est-ce que tous voient la même chose sur la Terre en même temps ?

Modèle de l'éclipse à l'échelle

· Dérouler une partie des trombones, ou utiliser des cure-dents et les insérer dans la balle de styromousse qui représente la Terre et dans la boule de pâte à modeler qui représente la Lune.

· Sur la règle, installer les balles à l'aide des trombones à une distance de 75 cm en les collant à l'aide du ruban adhésif, ou en fixant une pince. Ceci donne un modèle à l'échelle du système Terre-Lune.

· À l'extérieur, une journée ensoleillée, l'idée est d'aligner la Terre et la Lune du modèle pour créer des éclipses solaires et lunaires grâce au vrai Soleil. Poser les questions suivantes aux jeunes : Comment les astres devraient-ils être placés pour former une éclipse lunaire ? Et une éclipse solaire ? Pour une éclipse solaire : la Lune est entre le Soleil et la Terre, l'ombre de la Lune tombe sur la Terre. Pour une éclipse lunaire : la Terre est entre le Soleil et la Lune, l'ombre de la Terre tombe sur la Lune). Attention de ne pas créer d'ombre avec vos mains. Assurez-vous de bien dérouler les trombones complètement (de prendre des cure-dents suffisamment longs). Pour aider l'alignement, il est possible de prendre les ombres des balles au sol comme points de repère (mais attention, les ombres au sol ne représentent rien, dans le modèle!).

· Poser davantage de questions : Est-ce que l'ombre de la Lune couvre toute la Terre lors d'une éclipse solaire ? Est-ce que l'ombre de la Terre couvre toute la Lune lors d'une éclipse lunaire? Pendant une éclipse solaire/lunaire, qu'est-ce que les habitants de la Terre voient ? Voient-ils la même chose ?

· Faire remarquer aux jeunes que l'alignement parfait pour obtenir une éclipse solaire est difficile à obtenir, ce qui illustre bien pourquoi ces éclipses ne se produisent pas si souvent en un point donné sur Terre.

Étape 3 : Fabriquer le Projecteur de soleil (Démarche de conception)

· Découper dans votre papier cartonné un rectangle de 8 pouces sur 6 pouces (20 cm sur 15 cm). Découper un carré de 2 pouces (5 cm) de côté au centre comme sur le modèle ci-contre.

· Découper un carré de papier d'aluminium de 7,5 cm (3 po) de côté. Coller le papier d'aluminium sur le vide du carré. Le papier d'aluminium doit être lisse.

· Faire un trou au milieu de la feuille avec une punaise. Cette section peut demander l'aide de la personne enseignante selon son choix en termes de sécurité.

· Décorer le projecteur de soleil. Attention de ne pas couvrir le trou du papier d'aluminium.

· Note : en réalité, n'importe quel trou percé dans une feuille de papier fonctionnera! Le papier d'aluminium permet d'avoir un trou plus net.

Le 8 avril

Étape 4 : Observation de l'éclipse // S'il fait beau !

Utilisation du Projecteur de soleil

· Se placer dos au Soleil.

· Tenir le Projecteur de soleil au-dessus de son épaule pour laisser les rayons du Soleil passer à travers le trou.

· Tenir le carton ou la feuille blanche (l'écran) un peu plus loin de manière à ce que l'image du Soleil s'y forme

· Pour agrandir l'image, tenir l'écran plus loin du Projecteur.

Pendant la phase d'éclipse partielle (ou en tout temps pour les régions situées dans la zone d'éclipse partielle)

Tout autre objet qui a un ou plusieurs trous qui permettent de créer une ou des images du Soleil.

· Si vous n'avez pas de projecteur de soleil, aucun problème ! Vous pouvez regarder par terre ou sur un mur bien exposé au soleil l'ombre des arbres. Le feuillage créant de petits trous de manière naturelle, le Soleil ne projettera pas des ovales de lumière, mais des croissants !

Vous pouvez aussi utiliser des objets comme une passoire, ou même un biscuit Ritz pour créer des images du Soleil. Cela permettra de suivre l'évolution de l'éclipse : la forme du soleil va évoluer à mesure qu'il sera plus, puis moins caché par la Lune. Attention! Toujours se mettre dos au Soleil et faire passer sa lumière dans les trous. C'est l'image du Soleil qu'on regarde, pas le Soleil lui-même.

Pendant la phase d'éclipse totale (quelques secondes à quelques minutes, selon où vous vous trouvez)

- Profitez du spectacle! Contrairement aux phases partielles où on doit absolument regarder une projection du Soleil (ou avoir des lunettes munies de filtres solaires), il est possible de regarder sécuritairement vers le Soleil pendant les quelques secondes à quelques minutes où il est complètement éclipsé par la Lune.

Étape 4 : Observation de l'éclipse // Possible même si c'est nuageux

Mesure de la luminosité en cours d'éclipse

· Si l'on dispose d'un appareil photo muni d'une fonction manuelle (afin de fixer le temps de pose et l'ouverture de l'objectif), il est possible de réaliser des poses à intervalles réguliers (sur trépied photo de préférence). Assurez-vous de prendre une photo du paysage et non du soleil directement, à moins d'avoir un filtre spécialement fait pour les caméras, car l'exposition prolongée sans filtre adapté peut endommager l'appareil photo. Il est aussi possible d'utiliser des applications comme Arduino sur un téléphone intelligent pour voir l'évolution de la luminosité et enregistrer des mesures.

· Après l'éclipse, il sera possible de comparer les mesures ou les photos entre elles avec les élèves pour étudier le changement de luminosité.

Suivre l'éclipse en direct

· Il est possible de suivre les éclipses en direct sur le web. Voici des exemples de transmissions en direct lors de l'éclipse en Australie en 2023 : timeanddate et NASA (en anglais mais le visuel reste intéressant). Le 8 avril 2024, l'ASTROLab du Mont-Mégantic devrait proposer une diffusion en direct en français.

Étape 5 : Retour sur l'observation en classe

· Prendre le temps de faire un retour avec les élèves sur les différentes façons d'observer l'éclipse.

· Faire la mise en commun des observations.

Faire un retour sur l'éclipse avec Stellarium

· Si vous n'avez pas été en mesure d'observer l'éclipse le jour même, il est possible de trouver des vidéos en ligne ou d'utiliser Stellarium pour voir une simulation l'éclipse au moment où ça a eu lieu.

Étape 6 : Lien avec les arts et Univers social (voir ressources à consulter).

· Plusieurs activités en arts peuvent s'inspirer de l'expérience des élèves, ou encore du phénomène des ombres.

· Plusieurs repères culturels peuvent être abordés avec les élèves.

# data[].attributes.attachment_link.title
Éclipse totale du 8 avril 2024 (version pour le primaire)

# data[].attributes.attachment_link.description
Les élèves se préparent à observer une éclipse du Soleil à travers des activités sur les phases de la Lune, la modélisation de l'alignement de la Terre, la Lune et le Soleil et la fabrication d'un projecteur de Soleil.

# data[].attributes.attachment_link.readable_text
Les élèves se préparent à observer une éclipse du Soleil à travers des activités sur la modélisation de l'alignement de la Terre, la Lune et le Soleil, le calcul des distances entre Soleil-Terre et Terre-Lune et la fabrication d'un projecteur de Soleil.

Variable selon les dispositions choisies

Partout, mais en particulier les régions où l'éclipse sera totale: une partie de l'île de Montréal, la Montérégie, l'Estrie, le Centre-du-Québec, Chaudière-Appalaches et les Îles-de-la-Madeleine.
Vous pouvez consulter la carte du Québec avec les différentes régions : https://www.eclipsequebec.ca/carte/

Comprendre les relations mathématiques dans le système Soleil-Terre-Lune.

Comprendre les lignes de nœuds et leur rôle dans la fréquence des éclipses de Soleil.

Sciences et technologies :

Secondaire 1 et 2 : La lumière et ses propriétés; le phénomène des ombres; les éclipses

Modélisation avec cerceaux

- Ampoule de lumière faible pour le Soleil, de préférence rouge ou orange pour aider à prévenir l'éblouissement (facultatif)

- Cerceau représentant l'orbite de la Terre autour du Soleil

- Cerceau plus petit représentant l'orbite de la Lune autour de la Terre

- Balle solide de taille moyenne représentant la Terre

- Petite balle solide représentant la Lune

La boite à éclipses

- Une boite de carton vide, comme une boite à chaussures (plus elle est longue, plus l'image du Soleil sera grande, mais moins brillante)

- Une feuille de papier blanche

- Des ciseaux

- Du papier d'aluminium

- Une aiguille

- Du ruban adhésif

Projecteur de Soleil

- Papier cartonné ou boite de céréales recyclée.

- Feuille d'aluminium

- Ciseau

- Ruban adhésif

- Punaise

- Marqueurs ou crayon de couleur

- Carton ou feuille blanche (écran)

Mesure de la température et de la luminosité

-Luxmètre

-Photodiode

-Appareil photo avec filtre.

Préparation (avant le 8 avril)

Étape 0 : Activation des connaissances

Phases de la Lune et les ombres

Qu'est-ce qu'une ombre ?

Comment se forme une ombre ?

Quelle est la différence entre une éclipse de Lune et une éclipse de Soleil ?

Étape 1 : Modélisation au choix

Modèle de l'éclipse à l'échelle

Dérouler une partie des trombones, ou utiliser des cure-dents et les insérer dans la balle de styromousse qui représente la Terre et dans la boule de pâte à modeler qui représente la Lune.

Sur la règle, installer les balles à l'aide des trombones à une distance de 75 cm en les collant à l'aide du ruban adhésif, ou en fixant une pince. Ceci donne un modèle à l'échelle du système Terre-Lune.

À l'extérieur, une journée ensoleillée, l'idée est d'aligner la Terre et la Lune du modèle pour créer des éclipses solaires et lunaires grâce au vrai Soleil. Poser les questions suivantes aux jeunes : Comment les astres devraient-ils être placés pour former une éclipse lunaire ? Et une éclipse solaire ? Pour une éclipse solaire : la Lune est entre le Soleil et la Terre, l'ombre de la Lune tombe sur la Terre. Pour une éclipse lunaire : la Terre est entre le Soleil et la Lune, l'ombre de la Terre tombe sur la Lune). Attention, il ne faut pas créer d'ombre avec vos mains. Assurez-vous de dérouler les trombones complètement (de prendre des cure-dents suffisamment longs). Pour aider l'alignement, il est possible de prendre les ombres des balles au sol comme points de repère (mais attention, les ombres au sol ne représentent rien, dans le modèle!).

Modèle avec les cerceaux :

Inspiré de : Rosvick, J. (2008). An Interactive Demonstration of Solar and Lunar Eclipses. Astronomy Education Review, 7(2), 112‑121. https://doi.org/10.3847/AER2008031

Le but de cette démonstration est d'aider les élèves à visualiser l'orientation des orbites impliquées, à observer comment la Lune orbite autour de la Terre et comprendre pourquoi les éclipses ne sont pas observées à chaque nouvelle lune et à chaque pleine lune.

Fabrication

Percer des trous au centre des deux balles.

Repérer la section où le cerceau semble avoir été assemblé. Séparer le cerceau à ce point et y enfiler la boule qui représente la Terre.

Si le cerceau de l'orbite de la Lune est un anneau solide, il est possible de trancher à mi-chemin du trou percé la boule pour la glisser dans le cerceau et ensuite recoller les faces coupées.

Passer une des extrémités du cerceau de la Terre à travers l'orbite de la Lune.

Recoller le cerceau de l'orbite de la Lune qui a été précédemment coupé.

Modélisation

Demander aux élèves de tenir le cerceau horizontalement au-dessus de l'ampoule solaire, en s'assurant que le soleil est au centre du cerceau et dans le même plan.

Orienter le cerceau de l'orbite de la Lune avec une inclinaison exagérée par rapport au plan de l'orbite terrestre, puis montrer avec vos doigts l'intersection des orbites et demander aux élèves de visualiser une ligne.

Commencer la démonstration avec la Terre sur le côté du cerceau le plus proche des élèves. L'élève qui tient le cerceau se tient d'un côté. Orienter le cercle d'orbite de la Lune de manière à ce que la Lune se trouve dans une nouvelle phase lunaire, mais en dessous du plan de l'orbite terrestre. Tout en maintenant l'orientation et l'inclinaison du cerceau de l'orbite de la Lune, faire tourner le cerceau de la Lune jusqu'à ce que la Lune soit dans une phase de pleine lune; la Lune est maintenant au-dessus du plan de l'orbite de la Terre. En effectuant cette partie de la démonstration, expliquer que pour ces deux phases, les éclipses ne seront pas possibles parce que la Lune est au-dessus ou au-dessous de la Terre. Par conséquent, l'ombre de la Lune ne tombera pas sur la Terre, dans le cas d'une éclipse solaire, ni la Lune ne passera dans l'ombre de la Terre, dans le cas d'une éclipse lunaire.

Ensuite, l'élève fait tourner le cerceau dans le sens antihoraire (vu d'en haut) d'un quart de tour; maintenant, la Terre est du côté droit du cerceau, vu par la classe. Au cours de cette rotation, faire pivoter l'orbite lunaire autour d'un quart de tour, en veillant à ce que l'orientation de l'orbite ne soit pas modifiée pendant la rotation. Cette fois, lorsque les phases de la nouvelle lune et de la pleine lune sont démontrées, les élèves sont en mesure de voir que des éclipses sont possibles pour cet arrangement.

Étape 3 : Calculer les distances entre le Soleil-Terre et Terre-Lune

Activité de : https://www4.obs-mip.fr/wp-content-omp/uploads/sites/45/2021/06/dossier_peda_eclipse_version5generique.pdf

Avant de décrire le phénomène d'éclipse, il est important d'appréhender les tailles et distances comparées du Soleil, de la Terre et de la Lune :

Diamètre

Soleil 1 392 700 km

Terre 12 756 km

Lune 3 475 km

Distance Terre-Soleil (moyenne) : 149 597 871 km

Distance Terre-Lune (moyenne) : 383 398 km

Calculons maintenant le rapport entre les distances Terre-Soleil et Terre-Lune : RDS-L = 149 597 871 / 383 398 = 390

On constate que le diamètre de la Lune est environ 400 fois plus petit que celui du Soleil, mais qu'elle est aussi environ 400 fois plus proche de la Terre que ne l'est le Soleil : cette configuration exceptionnelle nous fait percevoir l'image du Soleil de la même taille que celle de la Lune.

On dit que les diamètres angulaires des deux astres sont comparables. Dans la réalité, ces diamètres angulaires varient légèrement puisque les distances Terre-Lune et Terre-Soleil varient (en raison des orbites elliptiques de la Lune et de la Terre. On comprend donc que, sous certaines conditions, la Lune puisse cacher le disque solaire. En revanche, dans certains cas, la Lune sera trop éloignée de la Terre pour cacher entièrement le disque solaire.

Étape 4: (Démarche de conception d'un outil pour observer l'éclipse)

La boite à éclipse

Ouvrir la boite et recouvrir l'une des faces intérieures courtes de papier blanc en utilisant le ruban adhésif.

Sur la face opposée au papier blanc, faire deux trous l'un à côté de l'autre, séparés d'au moins dix centimètres (un pour laisser entrer la lumière du Soleil et l'autre pour regarder à l'intérieur de la boite).

Coller du papier d'aluminium sur le trou pour le Soleil.

Utiliser l'aiguille pour percer un petit trou dans le papier d'aluminium.

Bien refermer la boite avec du ruban adhésif.

* Plus on augmente le diamètre du trou, plus l'image sera lumineuse... mais en contrepartie elle deviendra plus floue. À l'inverse, si l'on désire une image nette, on aura intérêt à diminuer le diamètre du trou (dans une certaine limite, l'image devenant trop ténue). - Plus on augmente la distance entre le trou et la surface (la feuille au fond de la boite) sur laquelle est projetée l'image, plus cette dernière est grande, mais moins elle est brillante. Il peut être intéressant de demander aux élèves de faire des hypothèses sur la distance et la circonférence du trou qui seraient optimales afin de pouvoir bien observer l'éclipse.

Fabriquer le Projecteur de soleil (Démarche de conception)

Découper dans votre papier cartonné un rectangle de 8 pouces sur 6 pouces (20 cm sur 15 cm). Découper un carré de 2 pouces (5 cm) de côté au centre comme sur le modèle ci-contre.

Découper un carré de papier d'aluminium de 7,5 cm (3 po) de côté. Coller le papier d'aluminium sur le vide du carré. Le papier d'aluminium doit être lisse.

Faire un trou au milieu de la feuille avec une punaise. Cette section peut demander l'aide de la personne enseignante selon son choix en termes de sécurité.

Décorer le projecteur de soleil. Attention de ne pas couvrir le trou du papier d'aluminium.

Note : en réalité, n'importe quel trou percé dans une feuille de papier fonctionnera! Le papier d'aluminium permet d'avoir un trou plus net.

Étape 5 : Observation de l'éclipse // S'il fait beau !

Utilisation du projecteur de soleil

· Se placer dos au Soleil.

· Tenir le projecteur de soleil au-dessus de son épaule pour laisser les rayons du Soleil passer à travers le trou.

· Tenir le carton ou la feuille blanche (l'écran) un peu plus loin de manière à ce que l'image du Soleil s'y forme

· Pour agrandir l'image, tenir l'écran plus loin du projecteur.

Pendant la phase d'éclipse partielle (ou en tout temps pour les régions situées dans la zone d'éclipse partielle)

Tout autre objet qui a un ou plusieurs trous qui permettent de créer une ou des images du Soleil.

· Si vous n'avez pas de projecteur de soleil, aucun problème ! Vous pouvez regarder par terre ou sur un mur bien exposé au soleil l'ombre des arbres. Le feuillage créant de petits trous de manière naturelle, le Soleil ne projettera pas des ovales de lumière, mais des croissants !

Vous pouvez aussi utiliser des objets comme une passoire, ou même un biscuit Ritz pour créer des images du Soleil. Cela permettra de suivre l'évolution de l'éclipse : la forme du soleil va évoluer à mesure qu'il sera plus, puis moins caché par la Lune. Attention! Toujours se mettre dos au Soleil et faire passer sa lumière dans les trous. C'est l'image du Soleil qu'on regarde, pas le Soleil lui-même.

Pendant la phase d'éclipse totale (quelques secondes à quelques minutes, selon où vous vous trouvez)

- Profitez du spectacle! Contrairement aux phases partielles où on doit absolument regarder une projectiondu Soleil (ou avoir des lunettes munies de filtres solaires), il est possible de regarder de manière sécuritaire vers le Soleil pendant les quelques secondes à quelques minutes où il est complètement éclipsé par la Lune.

Utilisation de la boite à éclipses

· Se placer dos au Soleil.

· En regardant dans le trou de la boite, ajuster sa position pour voir une projection du Soleil sur le papier blanc. L'image du Soleil devrait apparaitre au fonde de la boîte lorsque l'ombre de cette dernière projetée su sol est minimale.

· Lorsque la Lune commencera à cacher le Soleil, on pourra voir son disque couvrir progressivement le Soleil.

Étape 6 : Mesure de la luminosité et de la température

*Idéalement, il faut prévoir du temps pour prendre les mesures de température avant ou après l'éclipse à des fins de comparaison.

· Demander aux élèves s'ils pensent qu'il y aura une baisse de température en même temps que la baisse de luminosité ?

· Pense-t-il pouvoir la ressentir ?

· Comment pourrait-on le mesurer ?

Il est possible d'utiliser un luxmètre. Il fournit une indication de la luminosité ambiante sous la forme d'une échelle exprimée en EV (Exposure Value). Cette unité peut être conservée telle qu'elle pour tracer une courbe de son évolution, du début à la fin de l'éclipse (toutes les 10 minutes par exemple). Les mesures pourront être faites avec le posemètre dirigé vers le Soleil, mais aussi à l'opposée, devant un mur uni par exemple

On peut également utiliser une photodiode. L'unité arbitraire qu'on obtient en utilisant une photorésistance ou une photodiode (Illustration 40), reliée à un multimètre sur le calibre adéquat : mesure en Ohms pour la photorésistance (Illustration 40), mesure en Volts pour la photodiode permet aussi de prendre des mesures intéressantes.

Si l'on dispose d'un appareil photo muni d'une fonction manuelle (afin de fixer le temps de pose et l'ouverture de l'objectif), il est possible de réaliser des poses à intervalles réguliers (sur trépied photo de préférence). Assurez-vous de prendre une photo du paysage et non du soleil, à moins d'avoir un appareil spécialisé, car l'exposition prolongée sans filtre peut endommager l'appareil photo.

· Il est aussi possible d'utiliser des applications comme Arduino pour comparer la luminosité et enregistrée avec les mesures.

· Il est alors possible de comparer les photos entre elles (après l'éclipse) avec les élèves pour illustrer le changement de luminosité.

Étape 7 : Observation de l'éclipse // S'il fait ne fait pas beau !

Suivre l'éclipse en direct

· Il est possible de suivre l'éclipse en direct par exemple sur le site de l'AstroLab du Mont-Mégantic. Voici des exemples lors de l'éclipse en Australie l'année dernière : https://www.youtube.com/live/ifILl7GeZpE et https://www.youtube.com/watch?v=S2U3a1xXv8k

· Il est alors possible de comparer les photos entre elles (après l'éclipse) avec les élèves pour illustrer le changement de luminosité.

Étape 8 : Retour sur l'observation en classe:

Prendre le temps de faire un retour avec les élèves sur les différentes façons d'observer l'éclipse.

Faire la mise en commun des observations.

Faire un retour sur l'éclipse avec Stellarium

Si vous n'avez pas été en mesure d'observer l'éclipse le jour même, il est possible de trouver des vidéos en ligne ou d'utiliser Stellarium pour voir une simulation l'éclipse au moment où ça a eu lieu.

Étape 9 : Lien avec les arts et Univers social (voir ressources à consulter).

Plusieurs activités en arts peuvent s'inspirer de l'expérience des élèves, ou encore du phénomène des ombres.

Plusieurs repères culturels peuvent être abordés avec les élèves.

Éclipse :

- Explication du phénomène : https://www.eclipsequebec.ca/

- Guide d'utilisation de Stellarium : https://www.decouvertedelunivers.ca/niveau1

- Ressources et support pour le personnel enseignant : https://www.decouvertedelunivers.ca/eclipse

Boite à éclipse :

***Les deux ressources suivantes expliquent comment faire une boite à éclipse avec des boites de souliers recyclées. Celles-ci utilisent le même concept qu'expliqué plus haut : faire passer la lumière du Soleil à travers un petit trou vers un écran et regarder la projection du Soleil. Toutefois, ce dispositif ne permet pas toujours d'obtenir des images claires de l'éclipse car la distance entre le trou et l'écran n'est pas ajustable. L'avantage, si la distance est bonne, est qu'elles sont sombres, et donc le contraste est meilleur. Il peut être intéressant d'utiliser différentes manières de créer des projections du Soleil et de discuter leurs avantages et inconvénients en retour sur l'activité.

- Explication boite à éclipses solaires : https://www.asc-csa.gc.ca/fra/astronomie/eclipses/eclipses-solaires.asp

- Vidéo Débrouillard- comment fabriquer la boite à éclipses : https://www.youtube.com/watch?v=QVVsvGQz6YQ

-

Phases de la Lune

- Vidéo explicative des phases de la Lune : Phases de la lune - À la découverte de l'univers

- Calendrier des phases de la Lune : https://espacepourlavie.ca/phases-de-la-lune

- Fiche d'observation des phases de la Lune : https://espacepourlavie.ca/sites/espacepourlavie.ca/files/fiche_phases_lune.pdf

- Activité La lune de soir https://www.decouvertedelunivers.ca/_files/ugd/c07f8f_c76082493904456fa2ce222f7ef4109b.pdf

- Activité La lune de jour https://www.decouvertedelunivers.ca/_files/ugd/c07f8f_fe1f4719fe4c43809890628ccdf07d6b.pdf

- Activité d'observation du ciel et des exoplanètes : Défi - Explore le ciel... et les exoplanètes - Des exoplanètes à l'école

Repères culturels :

Inspiré de : https://leplanificateurdesciences.org/sae/systeme-terre-lune-soleil

-L'héliocentrisme:

-Les origines de notre calendrier:

-Face cachée de la lune:

- Le principe de Sténopé :

Les histoires d'éclipse : https://www4.obs-mip.fr/wp-content-omp/uploads/sites/45/2021/06/dossier_peda_eclipse_version5generique.pdf(p.28-29)

Les arts visuels :

Voici différentes pistes explorant le thème de l'ombre et de la lumière :

* Les théâtres d'ombres depuis la tradition asiatique jusqu'aux réalisations contemporaines

* Les œuvres de Rembrandt, Georges de la Tour, Picasso, ...

* Les œuvres de Diet Wiegman, de Tim Noble et Sue Webster ou de Kumi Yamashita : d'apparence informe ou aléatoire, elles révèlent leur aspect (et celui de leur ombre) une fois éclairées de manière adéquate.

Livres jeunesse en français sur le thème de la Lune (Soleil, Terre, Éclipse, Astronomie) : https://exoplanetes.umontreal.ca/les-suggestions-de-lecture-de-marie-eve/

Liste d'écoute de chansons sur le thème de la Lune: https://www.asc-csa.gc.ca/fra/multimedia/listes-de-lecture-sur-la-lune.asp

# data[].attributes.attachment_link.title
Éclipse totale du 8 avril 2024 (secondaire)

# data[].attributes.attachment_link.description
Les élèves se préparent à observer une éclipse du Soleil à travers des activités sur la modélisation de l'alignement de la Terre, la Lune et le Soleil, le calcul des distances entre Soleil-Terre et Terre-Lune et la fabrication d'un projecteur de Soleil. Variable selon les dispositions choisies Comprendre les relations mathématiques dans le système Soleil-Terre-Lune.

# data[].attributes.attachment_link.title
E comme Éclipse - Atelier sur les éclipses solaires - Complet

# data[].attributes.attachment_link.description
E comme Éclipse - Atelier sur les éclipses solaires* L'astrophysicienne Marie-Eve Naud de l'Institut Trottier de recherche sur les exoplanètes à l'Universit...

# data[].attributes.attachment_link.authors[].name
Institut Trottier de recherche sur les exoplanètes

# data[].attributes.attachment_link.title
E comme Éclipse BONUS | Observer une éclipse solaire sécuritairement #1 suite (jumelles)

# data[].attributes.headline
Comment fabriquer une boîte à éclipse solaire?

# data[].attributes.subject
Comment fabriquer une boîte à éclipse solaire?

# data[].attributes.attachment_link.readable_text
Sélection de la langue

Recherche

Vous êtes ici :

TRÈS IMPORTANT! Regarder le Soleil directement sans protection adéquate peut entraîner de graves problèmes, jusqu'à la perte partielle ou totale de la vue.
Pour plus d'informations

Lors d'une éclipse solaire, il est très important de protéger ses yeux. Depuis des centaines d'années, les astronomes se servent de différentes méthodes pour observer le Soleil de façon sécuritaire. Entre autres, la boîte à éclipse solaire permet d'observer une petite image du Soleil à travers une boîte fermée. Tu verras la Lune prendre des " bouchées " du Soleil!

Tu auras besoin de ce qui suit

Une boîte de carton vide (plus elle est longue, plus l'image du Soleil sera grande)

Une feuille de papier blanche

Des ciseaux

Du papier d'aluminium

Une aiguille

Du ruban adhésif

Comment construire la boîte à éclipse solaire

1. Ouvre la boîte et recouvre l'une des faces intérieures de papier blanc en utilisant le ruban adhésif.

2. Sur la face opposée au papier blanc, fais deux trous l'un à côté de l'autre, séparés d'au moins dix centimètres (un pour le Soleil et l'autre pour regarder).

3. Colle du papier d'aluminium par-dessus le trou pour le Soleil.

4. Utilise l'aiguille pour faire un petit trou dans le papier d'aluminium.

5. Referme bien la boîte avec du ruban adhésif.

6. Décore l'extérieur de ton nouveau projecteur pour le personnaliser à ton goût! (Facultatif)

Comment utiliser la boîte

1. Place toi dos au Soleil.

2. En regardant dans le trou de la boîte, ajuste ta position pour voir une projection du Soleil sur le papier blanc.

3. Lorsque la Lune commencera à cacher le Soleil, tu verras son ombre couvrir progressivement le Soleil.

Source : NASA.

Date de modification :

À propos de ce site

Agence spatiale canadienne

# data[].attributes.attachment_link.title
Comment fabriquer une boîte à éclipse solaire

# data[].attributes.attachment_link.description
Apprends comment fabriquer facilement une boîte à éclipse solaire.

# data[].attributes.headline
How to make your pinhole projector for eclipse?

# data[].attributes.subject
How to make your pinhole projector for eclipse?

# data[].attributes.attachment_link.readable_text
Language selection

Search

You are here:

VERY IMPORTANT! Looking directly at the Sun, without appropriate protection, can lead to serious problems such as partial or complete loss of eyesight.
For more information

During a solar eclipse, it is very important to protect your eyes. For hundreds of years, astronomers have used different methods to observe the Sun safely. One of them, the eclipse projector, allows you to view a small image of the Sun through a closed box. You will see the Moon taking "bites" out of the Sun!

You will need

An empty cardboard box (the longer it is, the larger the image of the Sun)

White paper

Scissors

Aluminum foil

A pin

Tape

How to build your projector

1. Open the box and, using tape, cover one of the inner sides with white paper.

2. On the opposite side of the white paper, cut two holes side by side and at least 10 cm apart (one for the Sun, the other to look in).

3. Cover the Sun hole with aluminum foil and tape it in place.

4. Grab your pin and poke a tiny hole in the aluminum foil.

5. Seal the box tightly.

6. Decorate the outside of your new projector to make it your own! (optional)

How to use your projector

1. Turn your back to the Sun.

2. Look through the eye hole and try to position yourself so that you see a projection of the Sun on the white paper.

3. When the Moon starts going over the Sun, you will see its shadow slowly covering the Sun.

Credit: NASA

Date modified:

About this site

# data[].attributes.attachment_link.title
How to make your pinhole projector for eclipse?

# data[].attributes.attachment_link.description
Learn how you can easily build your own eclipse projector.

# data[].attributes.attachment_link.description
Accédez facilement à l’information et aux services gouvernementaux.

# data[].attributes.attachment_link.description
Easily access government information and services.

# data[].attributes.attachment_link.readable_text
En 2024, un phénomène astronomique retient l'attention : l'éclipse solaire totale. Encerclez le 8 avril dans votre calendrier, car cet événement sera l'un des plus mémorables de votre vie.

Dernière chance avant 2106

L'éclipse solaire totale de ce printemps est à ne pas manquer parce qu'il n'y en a pas eu au Québec depuis 1972 et il n'y en aura pas d'autres avant 2106.

Le Québec aux premières loges

Les Québécois seront choyés et pourront contempler l'éclipse dans sa totalité dans plusieurs municipalités. L'éclipse durera le plus longtemps dans la région de Sherbrooke. À 15 h 27, le ciel s'y assombrira pendant 3 min 29 s, tandis qu'à Montréal, le phénomène se terminera après 1 min 28 s.

Un phénomène marquant à vie!

Une éclipse totale n'a rien à voir avec une éclipse partielle. Ce sera un spectacle à couper le souffle.

" Si vous êtes relativement proche de la zone de totalité, je vous encourage à vous déplacer jusque-là parce que le spectacle sera considérablement différent et sera bouleversant pour le reste de votre vie, j'en suis certain ", souligne Loïc Quesnel, coordonnateur d'activités scientifiques au Planétarium Rio Tinto Alcan.

Notez qu'il ne faut jamais observer une éclipse sans protéger ses yeux. Procurez-vous des lunettes protectrices ou fabriquez-vous une boîte à éclipse solaire.

À SURVEILLER : Éclipse totale : le Québec aux premières loges

En 2024, un phénomène astronomique retient l'attention : l'éclipse solaire totale. Encerclez le 8 avril dans votre calendrier, car cet événement sera l'un des plus mémorables de votre vie.

Dernière chance avant 2106

L'éclipse solaire totale de ce printemps est à ne pas manquer parce qu'il n'y en a pas eu au Québec depuis 1972 et il n'y en aura pas d'autres avant 2106.

Le Québec aux premières loges

Les Québécois seront choyés et pourront contempler l'éclipse dans sa totalité dans plusieurs municipalités. L'éclipse durera le plus longtemps dans la région de Sherbrooke. À 15 h 27, le ciel s'y assombrira pendant 3 min 29 s, tandis qu'à Montréal, le phénomène se terminera après 1 min 28 s.

Un phénomène marquant à vie!

Une éclipse totale n'a rien à voir avec une éclipse partielle. Ce sera un spectacle à couper le souffle.

" Si vous êtes relativement proche de la zone de totalité, je vous encourage à vous déplacer jusque-là parce que le spectacle sera considérablement différent et sera bouleversant pour le reste de votre vie, j'en suis certain ", souligne Loïc Quesnel, coordonnateur d'activités scientifiques au Planétarium Rio Tinto Alcan.

Notez qu'il ne faut jamais observer une éclipse sans protéger ses yeux. Procurez-vous des lunettes protectrices ou fabriquez-vous une boîte à éclipse solaire.

À SURVEILLER : Éclipse totale : le Québec aux premières loges

# data[].attributes.attachment_link.title
Éclipse solaire totale : le phénomène à ne pas manquer en 2024 - MétéoMédia

# data[].attributes.attachment_link.description
En 2024, un phénomène astronomique retient l'attention : l'éclipse solaire totale. Encerclez le 8 avril dans votre calendrier, car cet événement sera l'un des plus mémorables de votre vie.

# data[].attributes.headline
Time and date: solar eclipse informations

# data[].attributes.subject
Time and date: solar eclipse informations

# data[].attributes.attachment_link.readable_text
The path of totality for this total solar eclipse runs through Mexico, the United States, and Canada.
What happens during a total solar eclipse?
Our timeanddate team will be broadcasting the eclipse LIVE from the USA.

This eclipse is visible in Washington DC - go to local timings and animation

What the Eclipse Will Look Like near the Maximum Point

The animation shows what the eclipse approximately looks like near the maximum point. The curvature of the Moon's path is due to the Earth's rotation.
How accurate is the eclipse calculation

Live Eclipse Animation will start at:

Live Eclipse Animation has ended.

You are using an outdated browser, to view the animation please update or switch to a modern browser. Alternatively you can view the old animation by clicking here.

Where to See the Eclipse

Try our new interactive eclipse maps. Zoom in and search for accurate eclipse times and visualizations for any location.

Path of the Eclipse Shadow

Regions seeing, at least, a partial eclipse: West in Europe, North America, North in South America, Pacific, Atlantic, Arctic.

Expand for a list of selected cities where at least part of the total eclipse is visible

Expand for a list of selected cities where the partial eclipse is visible

This eclipse is visible in Washington DC - go to local timings and animation

Eclipse Shadow Path

Portion of Sun covered by the Moon (Eclipse obscuration)

The dark areas symbolize night and twilight.

3D Eclipse Animation

Portion of Sun covered by the Moon (Eclipse obscuration)

The dark areas symbolize night and twilight.

Note: The animation follows the eclipse shadow from west to east, its point of view moving around the planet at a greater speed than Earth's rotation. If you don't take into account this rapid change of perspective, it may look like Earth is spinning in the wrong direction.

The narrow path of totality-where the Moon covers the Sun completely, causing a total eclipse-runs through Mexico (from Sinaloa to Coahuila), the USA (from Texas to Maine), and Canada (from Ontario to Newfoundland). A partial eclipse will be visible across nearly all of North America, and a sliver of western Europe.

When the Eclipse Happens Worldwide - Timeline

The eclipse starts at one location and ends at another. The times below are actual times (in UTC) when the eclipse occurs. This calculation uses a Delta T value of 69.2 seconds.

Event

UTC Time

Time in Washington DC*

First location to see the partial eclipse begin

Apr 8 at 15:42:15

Apr 8 at 11:42:15 am

First location to see the full eclipse begin

Apr 8 at 16:38:52

Apr 8 at 12:38:52 pm

Maximum Eclipse

Apr 8 at 18:17:21

Apr 8 at 2:17:21 pm

Last location to see the full eclipse end

Apr 8 at 19:55:35

Apr 8 at 3:55:35 pm

Last location to see the partial eclipse end

Apr 8 at 20:52:19

Apr 8 at 4:52:19 pm

* These local times do not refer to a specific location but indicate the beginning, peak, and end of the eclipse on a global scale, each line referring to a different location. Please note that the local times for Washington DC are meant as a guideline in case you want to view the eclipse via a live webcam. They do not mean that the eclipse is necessarily visible there.
Eclipse calculations usually accurate to a few seconds. Eclipses visible in Washington DC. Next Total Solar Eclipse will be on Aug 12, 2026.
Countries Where the Eclipse Is Visible

How Many People Can See This Eclipse?

Number of People Seeing...

Number of People*

Fraction of World Population

* The number of people refers to the resident population (as a round number) in areas where the eclipse is visible. timeanddate has calculated these numbers using raw population data provided by the Center for International Earth Science Information Network (CIESIN) at Columbia University. The raw data is based on population estimates from the year 2000 to 2020.

All eclipses 1900 - 2199

Need some help?

# data[].attributes.attachment_link.title
Total Solar Eclipse on April 8, 2024 (Great North American Eclipse )

# data[].attributes.attachment_link.description
Total solar eclipse on Monday, April 8, 2024: Where and when is the Sun eclipse visible? Path map, animation, and local times.

# data[].attributes.headline
National geographic : Meet the 'shadow lovers:' three men who have each witnessed more total eclipses than anyone

# data[].attributes.subject
National geographic : Meet the 'shadow lovers:' three men who have each witnessed more total eclipses than anyone

# data[].attributes.attachment_link.readable_text
The moon moves between the Earth and the sun: 21 August, 2017, Richland, South Carolina. This day saw a total eclipse move across a narrow strip of the United States - with a partial eclipse visible in many other countries.

Photograph by DOD Photo, Alamy

At lunchtime on December 14 th, the people in the Chilean town of Villarrica will be cast into darkness. Looking west, they will see a grey shadow rolling in from the direction of the Pacific Ocean. As our moon eclipses the sun, blocking out its light, the temperature will drop, birds will start roosting, cicadas will chirrup, and stars will appear bright in the midday sky.

Then the path of the eclipse - or path of totality, as it's known - will continue eastwards, crossing the Andes into Argentina, tracing a broad line across Northern Patagonia and out into the Atlantic Ocean.

Among the many foreigners hoping to witness this astronomical event are American trio Glenn Schneider, Jay Pasachoff and John Beattie. Each man individually holds the equal world record for observing more total solar eclipses than any other human being in history: an impressive 35 each. Pandemic travel restrictions have impinged on their plans for a 36 th, however.

65-year-old Schneider (an astronomer at the University of Arizona's Steward Observatory) and 77-year-old Pasachoff (professor of astronomy at Williams College, in Massachusetts, and head of a working group on solar eclipses at the International Astronomical Union) are both unable to travel. At the time of writing, only Beattie (a proofreader from New York, in his early 70s) was intending to visit.

Observers in Siak, Riau, Indonesia watch the 2019 total eclipse through specially filtered glasses. Eclipses take on different resonances, from spiritual experiences to scientific fascinations.

Photograph by Zuma Press, Inc., Alamy

Adventures of the umbraphiles

These three astronomers - all originally from New York City - are known as eclipse-chasers, or umbraphiles (shadow-lovers). In pursuit of their passion, they have dedicated much of their spare time and money travelling to locations within the path of totality - exotic destinations such as Easter Island, Siberia, the Zambezi River, Java, Kenya, China's Hubei province, the Aleutian Islands, the Arctic and the Antarctic. In last-minute scrambles to find cloud-free viewing spots, they have had to hire local drivers, charter aeroplanes, embark on boat trips, or search desperately for high ground. While Pasachoff funds his trips through research grants, Schneider and Beattie often have to pay for their own passage.

Villarrica, in Chile, is set to be the dramatic location the path of totality for an eclipse on 14th December, 2020.

Photograph by Panther Media GmbH, Alamy

A solar eclipse occurs when the Sun, Moon and Earth align - a phenomenon known as syzygy. There are four types: a total solar eclipse, when the Moon completely occludes the Sun, is by far the most dramatic; a partial solar eclipse is when the Moon passes in front of the Sun, but off centre so that only part of the Sun's disc is obscured; an annular solar eclipse is when the Moon passes dead centre in front of the Sun but appears too small to fully occlude its disc (because the Moon's orbit is elliptical); and a hybrid solar eclipse is a combination of a total and an annular eclipse.

Total solar eclipses are rare, occurring somewhere on our planet only once every 16 months or so. The last total eclipse to pass across the UK was in August 1999, over Cornwall and Devon. The next won't arrive on these shores until September 2090.

In Madras, Oregon, people watch the total eclipse in 2017.

The problem of size

Unfortunately, our nation is so compact (approximately one two thousandth of the planet's surface area), that it is poorly served by total eclipses. People living in countries which span multiple degrees of latitude have a far greater chance of witnessing them. Chile, which stretches from well inside the tropics, almost as far down as the Antarctic Circle, is a great example. By the end of this century alone, this South American nation will have had seven total eclipses and nine annular eclipses crossing its territory.

Glenn Schneider. Remarkably equal with his fellow observers, he has racked up 35 total eclipses.

Photograph by Glenn Schneider

Of course, rarity adds value, and anyone who has witnessed a total solar eclipse will tell you what an electrifying, emotional spectacle it can be. First there is the lunar shadow which rolls in rapidly (normally from the west), imposing nighttime in the middle of the day. Then there is the beauty of the corona, as the Moon occludes the bright disk of the Sun. There is the Baily's beads effect, when sunlight shines through the valleys on the edge of the Moon. And, at the start and end of totality, there is the diamond ring effect, when the last bit of sunlight disappears and then later reappears like a sparkling diamond from behind the edge of the Moon.

"I stood there with my binoculars dangling around my neck, looking at that hole in the sky. I couldn't move. I didn't take a single photo. I was mesmerised."

For first-time observers, the effects can be overwhelming. Some people are stunned into silence, some scream, some cheer, some even burst into tears.

"You really feel your place in the universe," Schneider tells National Geographic UK. "It's a connection to celestial mechanics in a very visceral way. It connects the scale of human experience to celestial experience. It ties into people's base emotions."

A trick of light and space

The reason we are able to experience total solar eclipses is all down to a wonderful astronomical quirk. The Sun's diameter is 400 times larger than the Moon's and, coincidentally, the Sun is, on average, 400 times further away from the Earth than the Moon. This makes both bodies appear the same size in the sky, so that, during a total solar eclipse, the Moon overlays the Sun perfectly.

It's an equally wonderful quirk that there are intelligent beings alive to observe eclipses. Every year, the Moon's orbit pulls away from the Earth by 3.78 cm so that, hundreds of millions of years from now, it will be too far away to block out the Sun. Right now, in the Earth's 4.5 billion-year history, cosmic conditions are perfect.

Jay Pasachoff at the Palomar observatory, near San Diego. His first total eclipse, in 1959, was viewed from an aircraft chartered by his astronomy professor.

Photograph by Jay Pasachoff

Pasachoff will never forget his first total eclipse. As a freshman astronomy student at Harvard University, he was studying under an eclipse expert called Professor Donald Menzel. "There happened to be a total solar eclipse a couple of years after school started, on October 12, 1959," he tells National Geographic UK. "Professor Menzel borrowed a DC3 to fly out of Boston to watch it out the side windows. Eleven of our freshman seminar group were on board. The effect was so dazzling that I was hooked." Pasachoff once described eclipse-watching as "like going to the seventh game of the World Series with the score tied in the ninth inning."

Schneider lost his eclipse virginity 11 years later, in 1970. He was a schoolboy in New York City at the time, and decided to head down to North Carolina for the perfect vantage point. Having done his research, he knew he would have only two minutes and 54 seconds to observe the phenomenon. In advance, he dutifully rehearsed how he was going to spectate, using binoculars, telescopes and cameras.

"As the Moon's shadow approached, and just before totality, I was thunderstruck," he remembers. "It was the most incredible thing I'd ever seen: a wall of darkness coming across and enveloping us; a very high-contrast umbra; the advent of second contact and the diamond ring. It was all unbelievable. I stood there with my binoculars dangling around my neck, looking at that hole in the sky. I couldn't move. I didn't take a single photo. I was mesmerised. It froze me right to the spot, and changed my perception of what I was going to do with the rest of my life."

A multiple exposure shot at five minute intervals showing the moon moving into and out of total eclipse above Moose River, Ontario, in 1963. Were an aircraft to track the movement of the shadow, it would be following the path of totality - and it's a common pursuit amongst serious 'umbraphiles.'

Photograph by Laird S. Brown, National Geographic Creative

Since then, Schneider has dedicated much of his spare time to what he admits is "an umbraphillic obsession". "It's not only an addiction, but an affliction, and a way of life," he explains.

One of his most memorable experiences was in 2002, in the Australian outback, when he planted himself near the very end of the path of totality, where the darkness rose up into the sky rather than across the surface of the Earth. "As totality was ending, we looked straight up and saw this elongated oval of darkness getting smaller and smaller, lifting back up into space," he remembers. "It was one of the most amazing things I've ever seen."

1986 proved to be an exceptional eclipse, too. This time Schneider and four other umbraphiles hired a Cessna jet and pursued a hybrid eclipse through the Denmark Strait between Greenland and Iceland. They were lucky to intercept it since this was in the days before GPS. "It was all over so quickly, if you'd sneezed, you would have missed it."

In 2013, he travelled with colleagues to northern Kenya, to the remote region around Lake Turkana. Preparing themselves for totality, they noticed a "biblical sandstorm" on the horizon. Desperate not to miss the eclipse, they all leapt on board two chartered aeroplanes, flying through and then above the storm for a perfect view.

Last year's eclipse in the Southern Pacific was also observed through an aeroplane window. Schneider worked with a specialist travel agency to devise a flight plan for a chartered Boeing 787 to intercept the eclipse at precisely the right moment. On July 2 nd, as part of a group of paying customers, he took off from Easter Island, heading north. By following the path of totality in a speeding jet, they were able to extend the eclipse to eight and a half minutes - far longer than if they had been stationary on the ground. "That option was just too appealing," says Schneider, whose computations earned him a free seat on the plane.

While he did carry out an experiment to measure the Sun's coronal emissions, his motivation was far more aesthetical than scientific - as it always is, he stresses. For Pasachoff, however, eclipses are a key component of his everyday work as an astronomer. Despite being unable to make it to Chile on December 14 th, he is collaborating with scientists who will be there, conducting various experiments. He is understandably dismayed at not being able to attend in person.

"This will be the first total solar eclipse I have missed since 1976," he says. "I still hope that I can get some scientific results."

When it became clear to Schneider he couldn't travel to Chile either, he says he felt "devastated at the horrible realisation".

Should Beattie make it, however, he will clock up 36 total solar eclipses, overtaking Schneider and Pasachoff's current tally. Nevertheless, Schneider stresses that umbraphilia is a science, not a sport. "None of us do this for record keeping or as competitive sport," he says. "That's not what this is about."

He insists there's no rivalry between the three men. "A fraternity," is how he describes them. "We're all on the same team."

Besides, it's likely these three astronomers will reunite in just under a year's time. On December 4 th 2021, they and other umbraphiles will board a chartered passenger jet in the southern Chilean city of Punta Arenas before intercepting a total solar eclipse just after sunrise, 12,000 metres above the South Atlantic Ocean, in between the Falkland Islands and South Georgia.

"From our aircraft, totality will be seen with the totally-eclipsed Sun very low above the terrestrial horizon," says Schneider who is calculating the flight plan. "The long, dark, conical umbral shadow will sweep over our aircraft with its axis tangent to the surface of the Earth. This will be a truly amazing sight to behold."

Dominic Bliss is a freelance journalist based in London. Follow him on Twitter.

# data[].attributes.attachment_link.title
Meet the 'shadow lovers:' three men who have each witnessed more total eclipses than anyone

# data[].attributes.attachment_link.description
Chasing the phenomenon has been a decades-long adventure. But on the eve of the latest, COVID-19 has cast its own shadow.

# data[].attributes.attachment_link.provider_name
EarthSky | Updates on your cosmos and world

# data[].attributes.attachment_link.readable_text
Astronomy Essentials Tonight

We're counting down the days to the total solar eclipse on April 8. And we're looking back to the year 1919, to the eclipse that made Albert Einstein famous. At that time, Einstein's theory of General Relativity was just 4 years old. It seemed preposterous. How could it be proven? An eclipse was the answer. Join EarthSky's Deborah Byrd in the video above.
Watch the full Countdown to Eclipse series.
If you like our videos, please share them and subscribe to our YouTube channel.

Total solar eclipse of April 8, 2024

Partial eclipse begins: at 15:42 UTC (11:42 a.m. EDT) on April 8.
Total eclipse begins: at 16:38 UTC (12:38 p.m. EDT) on April 8.
Greatest eclipse: at 18:17 UTC (2:17 p.m. EDT) on April 8.
Total eclipse ends: at 19:55 UTC (3:55 p.m. EDT) on April 8.
Partial eclipse ends: at 20:52 UTC (4:52 p.m. EDT) on April 8.
Note: The instant of greatest eclipse - when the axis of the moon's shadow cone passes closest to Earth's center - takes place at 18:17 UTC (2:17 p.m. EDT). It's a relatively long total eclipse with a duration of totality lasting 4.47 minutes.

Remember that the number one rule for solar eclipse observing is to make sure you protect your eyes by using an appropriate filter.
Need eclipse glasses? Get 'em here, but order soon!
Don't miss the great eclipse maps below.

EarthSky lunar calendars are back in stock! And we're guaranteed to sell out, so get one while you can. Your support means the world to us and allows us to keep going. Purchase here..

Moon, constellation, Saros

Greatest eclipse takes place one day after the moon reaches perigee, its closest point to Earth for the month. During the April 8, 2024, eclipse, the sun is located in the direction of the constellation Aries.

This eclipse has a magnitude of 1.0566.

The Saros catalog describes the periodicity of eclipses. The eclipse belongs to Saros 139. It is number 30 of 71 eclipses in the series. All eclipses in this series occur at the moon's ascending node. The moon moves southward with respect to the node with each succeeding eclipse in the series.

Cities where the total solar eclipse is visible

Next eclipse and eclipse seasons

The total solar eclipse of April 8, 2024, is preceded two weeks earlier by a penumbral lunar eclipse on March 24, 2024.

These eclipses all take place during a single eclipse season.

An eclipse season is an approximate 35-day period during which it's inevitable for at least two (and possibly three) eclipses to take place. The next eclipse season has three eclipses: September 17-18, October 2 and October 17, 2024.

Maps and data

Find maps and eclipse timings below. Remember to convert UTC to your time.

* Timeanddate.com: to get the exact timing of the eclipse from your location.
* Orthographic Map: detailed global map of eclipse visibility.
* Google Map: interactive map of the eclipse path.
* Path Table: coordinates of the central line and path limits.
* Circumstances Table: eclipse times for hundreds of cities.
* Saros 139 Table: data for all eclipses in the Saros series.
* Additional tables and data.

Here is what a total solar eclipse looks like

Eclipse maps from Great American Eclipse

Michael Zeiler of GreatAmericanEclipse.com has generously given us permission to share his eclipse maps for the total solar eclipse. Here you can get a better idea of where you'll want to be and when to see this unique phenomenon.

Which location is closest to you?

Maps for the timing of the eclipse

How long will the eclipse last?
Read more: Total solar eclipse of April 8, 2024, from Michael Zeller Watch the full Countdown to Eclipse series.
Bottom line: We're counting down to the April 8, 2024, eclipse, which will cross North America. How did a total solar eclipse prove Einstein's theory right, in the year 1919?
Read more from EarthSky: Tides, and the pull of the moon and sun See photos of the December 2021 solar eclipse EarthSky's monthly planet guide: Visible planets and more

# data[].attributes.attachment_link.title
36 days to go! The total solar eclipse that made Einstein famous

# data[].attributes.attachment_link.description
Astronomy Essentials Tonight We're counting down the days to the total solar eclipse on April 8. And we're looking back to the year 1919, to the eclipse that made Albert Einstein famous. At that time, Einstein's theory of General Relativity was just 4 years old. It seemed preposterous.

# data[].attributes.attachment_link.title
Comment observer l’éclipse solaire sans endommager ses yeux? | Info | Radio-Canada

# data[].attributes.attachment_link.description
Il existe des manières sécuritaires de regarder l’éclipse sans lunettes spéciales. En voici quelques-unes.

# data[].attributes.attachment_link.title
Tout savoir sur l'éclipse solaire totale du 8 avril 2024 | Info | Radio-Canada

# data[].attributes.attachment_link.description
À moins d'un mois du spectaculaire événement astronomique, Marie-Audrey Houle nous offre un cours 101 sur l'éclipse solaire totale du 8 avril 2024.

# data[].attributes.attachment_link.readable_text
Les élèves madelinots seront les seuls à bénéficier d'une activité d'observation de l'éclipse solaire totale dans un cadre scolaire. Les centres de service scolaires de la Gaspésie ont opté pour une suspension de cours d'une demi-journée en réponse aux défis logistiques imposés par l'événement.

Comme l'éclipse solaire peut endommager la rétine et causer des problèmes de vision permanents si elle est regardée sans protection, l'événement soulevait des questions pour la sécurité des élèves.

Les de services scolaires du territoire n'avaient pas pris de décision le mois dernier, puisqu'ils attendaient de connaître les orientations de Québec.

Ceux et celles qui le désirent seront ensuite conviés à se rendre à la polyvalente en compagnie de leurs parents. Les cours seront maintenus à la polyvalente. Après la sortie des classes, les élèves du secondaire pourront rester à l'école pour prendre part à des activités avec des astronomes amateurs dès 15 h.

Il n'était pas possible pour sa directrice générale, Brigitte Aucoin, de nous accorder une entrevue mardi.

Des suspensions d'une demi-journée ailleurs

Si l'orientation première de Québec était un maintien des cours, plusieurs conditions, dont un retour à la maison sécuritaire, devaient être mises de l'avant pour garder les élèves dans les écoles. Ce que ça veut dire, c'est aucun élève dans les transports scolaires entre 14 h 11 et 16 h 45 , résume Sandra Nicol, directrice générale du René-Lévesque.

La sécurité de nos élèves est notre priorité absolue. Bien que l'éclipse solaire soit un événement fascinant, cela présente également des défis logistiques considérables en matière de gestion du transport scolaire.

À titre d'exemple, pour certaines écoles, les départs des élèves se seraient déroulés seulement vers 18 h, entraînant des problèmes de logistique à plusieurs niveaux , peut-on lire dans un communiqué acheminé mardi matin par le des Chic-Chocs.

La Commission scolaire Eastern Shores s'est concertée, dans un souci de cohérence, avec les René-Lévesque et des Chic-Chocs et devrait statuer dans le même sens. Au moment de publier ces lignes, Radio-Canada n'avait toutefois pas été en mesure de vérifier avec la direction si elle emboîtait le pas avec les mêmes mesures.

Présentement, ce qu'on nous indique, c'est qu'elles sont en rupture de stock. Certaines que l'on peut trouver ne sont pas nécessairement toujours de qualité, alors on nous a mis en garde de faire bien attention dans l'achat des lunettes , explique la directrice générale intérimaire du Monts-et-Marées, Marie-Pierre Guénette.

# data[].attributes.attachment_link.title
Les écoles de la région se préparent pour l'éclipse du 8 avril

# data[].attributes.attachment_link.description
Si les CSS gaspésiens ont opté pour une demi-journée pédagogique, l'éclipse solaire du 8 avril pourra être observée à la polyvalente des Îles

# data[].attributes.headline
CBC : You've likely never seen a total solar eclipse. Here's where and how to watch April's upcoming show

# data[].attributes.subject
CBC : You've likely never seen a total solar eclipse. Here's where and how to watch April's upcoming show

# data[].attributes.headline
CBC : 2024 Total Solar Eclipse: Why you’ll never see it again

# data[].attributes.subject
CBC : 2024 Total Solar Eclipse: Why you’ll never see it again

# data[].attributes.attachment_link.readable_text
Eclipse, in astronomy, complete or partial obscuring of a celestial body by another. An eclipse occurs when three celestial objects become aligned.

total solar eclipse Joseph Matus-MSFC/NASA

From the perspective of a person on Earth, the Sun is eclipsed when the Moon comes between it and Earth, and the Moon is eclipsed when it moves into the shadow of Earth cast by the Sun. Eclipses of natural satellites (moons) or of spacecraft orbiting or flying past a planet occur as the bodies move into the planet's shadow. The two component stars of an eclipsing binary star move around each other in such a way that their orbital plane passes through or very near Earth, and each star periodically eclipses the other as seen from Earth.

When the apparent size of the eclipsed body is much smaller than that of the eclipsing body, the phenomenon is known as an occultation. Examples are the disappearance of a star, nebula, or planet behind the Moon or the vanishing of a natural satellite or spacecraft behind some body of the solar system.

A transit occurs when, as viewed from Earth or another point in space, a relatively small body passes across the disk of a larger body, usually the Sun or a planet, eclipsing only a very small area. Mercury and Venus, for example, periodically transit the Sun, and a natural satellite may transit its planet. Extrasolar planets (e.g., HD 209458b) have been discovered when they perform a transit of their stars.

Phenomena observed during eclipses

The Moon, when full, may enter the shadow of Earth. The motion of the Moon around Earth is from west to east ( see the figure of a lunar eclipse, in which the view of Earth is from above its North Pole). For an observer facing south, the shadowing of the Moon begins at its left edge (if the Moon were north of the observer, as, for example, in parts of the Southern Hemisphere, the opposite would be true). If the eclipse is a total one and circumstances are favourable, the Moon will pass through the umbra, the darkest part of the shadow, in about two hours. During this time the Moon is usually not completely dark. A part of the sunlight, especially the redder light, penetrates Earth's atmosphere, is refracted into the shadow cone, and reaches the Moon. Meteorological conditions on Earth strongly affect the amount and colour of light that can penetrate the atmosphere. Generally, the totally eclipsed Moon is clearly visible and has a reddish brown, coppery colour, but the brightness varies strongly from one eclipse to another.

Encyclopædia Britannica, Inc.

Before the Moon enters the umbra and after it leaves the umbra, it must pass through the penumbra, or partial shadow. When the border between umbra and penumbra is visible on the Moon, the border is seen to be part of a circle, the projection of the circumference of Earth. This is a direct proof of the spherical shape of Earth, a discovery made by the ancient Greeks. Because of Earth's atmosphere, the edge of the umbra is rather diffuse, and the times of contact between the Moon and the umbra cannot be observed accurately.

lunar eclipse NASA

During the eclipse the surface of the Moon cools at a rate dependent on the constitution of the lunar soil, which is not everywhere the same. Many spots on the Moon sometimes remain brighter than their surroundings during totality-particularly in their output of infrared radiation-possibly because their heat conductivity is less, but the cause is not fully understood.

An eclipse of the Moon can be seen under similar conditions at all places on Earth where the Moon is above the horizon.

key people

related topics

# data[].attributes.attachment_link.description
Eclipse, in astronomy, complete or partial obscuring of a celestial body by another. From the perspective of a person on Earth, the Sun is eclipsed when the Moon comes between it and Earth, and the Moon is eclipsed when it moves into the shadow of Earth cast by the Sun.

# data[].attributes.attachment_link.readable_text
eclipse, in astronomy, complete or partial obscuring of a celestial body by another. An eclipse occurs when three celestial objects become aligned.

From the perspective of a person on Earth, the Sun is eclipsed when the Moon comes between it and Earth, and the Moon is eclipsed when it moves into the shadow of Earth cast by the Sun. Eclipses of natural satellites (moons) or of spacecraft orbiting or flying past a planet occur as the bodies move into the planet's shadow. The two component stars of an eclipsing binary star move around each other in such a way that their orbital plane passes through or very near Earth, and each star periodically eclipses the other as seen from Earth.

When the apparent size of the eclipsed body is much smaller than that of the eclipsing body, the phenomenon is known as an occultation. Examples are the disappearance of a star, nebula, or planet behind the Moon or the vanishing of a natural satellite or spacecraft behind some body of the solar system.

A transit occurs when, as viewed from Earth or another point in space, a relatively small body passes across the disk of a larger body, usually the Sun or a planet, eclipsing only a very small area. Mercury and Venus, for example, periodically transit the Sun, and a natural satellite may transit its planet. Extrasolar planets (e.g., HD 209458b) have been discovered when they perform a transit of their stars.

Lunar eclipse phenomena
The Moon, when full, may enter the shadow of Earth. The motion of the Moon around Earth is from west to east ( see the figure of a lunar eclipse, in which the view of Earth is from above its North Pole). For an observer facing south, the shadowing of the Moon begins at its left edge (if the Moon were north of the observer, as, for example, in parts of the Southern Hemisphere, the opposite would be true). If the eclipse is a total one and circumstances are favourable, the Moon will pass through the umbra, the darkest part of the shadow, in about two hours. During this time the Moon is usually not completely dark. A part of the sunlight, especially the redder light, penetrates Earth's atmosphere, is refracted into the shadow cone, and reaches the Moon. Meteorological conditions on Earth strongly affect the amount and colour of light that can penetrate the atmosphere. Generally, the totally eclipsed Moon is clearly visible and has a reddish brown, coppery colour, but the brightness varies strongly from one eclipse to another.

Before the Moon enters the umbra and after it leaves the umbra, it must pass through the penumbra, or partial shadow. When the border between umbra and penumbra is visible on the Moon, the border is seen to be part of a circle, the projection of the circumference of Earth. This is a direct proof of the spherical shape of Earth, a discovery made by the ancient Greeks. Because of Earth's atmosphere, the edge of the umbra is rather diffuse, and the times of contact between the Moon and the umbra cannot be observed accurately.

During the eclipse the surface of the Moon cools at a rate dependent on the constitution of the lunar soil, which is not everywhere the same. Many spots on the Moon sometimes remain brighter than their surroundings during totality-particularly in their output of infrared radiation-possibly because their heat conductivity is less, but the cause is not fully understood.

An eclipse of the Moon can be seen under similar conditions at all places on Earth where the Moon is above the horizon.

Solar eclipse phenomena
Totality at any particular solar eclipse can be seen only from a narrow belt on Earth, sometimes only 150 km (90 miles) wide. The various phases observable at a total solar eclipse are illustrated in the top portion of the figure. The designation "first contact" refers to the moment when the disk of the Moon, invisible against the bright sky background, first touches the disk of the Sun. The partial phase of the eclipse then begins as a small indentation in the western rim of the Sun becomes noticeable. The dark disk of the Moon now gradually moves across the Sun's disk, and the bright area of the Sun is reduced to a crescent. On Earth the sunlight, shining through gaps in foliage and other small openings, is then seen to form little crescents of light that are images of the light source, the Sun. Toward the beginning of totality, the direct light from the Sun diminishes very quickly, and the colour changes. The sky near the zenith becomes dark, but along the horizon Earth's atmosphere still appears bright because of the narrow extent of the umbra of the Moon's shadow on Earth. The scattered light coming in from a distance beyond the umbral region produces the effect of twilight. Animals may react with fear, humans often with awe. Birds may go to roost as they do at sunset.

As the tiny, narrow crescent of sunlight disappears, little bright specks remain where depressions in the Moon's edge, the limb, are last to obscure the Sun's limb. These specks are known as Baily's beads, named for the 19th-century English astronomer Francis Baily, who first drew attention to them. The beads vanish at the moment of second contact, when totality begins. This is the climax of the eclipse. The reddish prominences and chromosphere of the Sun, around the Moon's limb, can now be seen. The brighter planets and stars become visible in the sky. White corona l streamers extend from the Sun to a distance of several solar radii. The air temperature on Earth in the path of totality falls by some degrees. The light of totality is much brighter than that of the full moon but is quite different in colour. The duration of totality is brief, typically lasting two to five minutes.

The moment of third contact occurs when the Moon's west edge first reveals the Sun's disk. Many of the phenomena of second contact appear again, in reverse order. Suddenly the first Baily's bead appears. More beads of light follow, the Sun's crescent grows again, the corona disappears, daylight brightens, and the stars and planets fade from view. The thin crescent of the Sun gradually widens, and about one and a quarter hours later the eclipse ends with fourth contact, when the last encroachment made by the Moon on the Sun's rim disappears.

During the partial phase, both before and after totality, it is absolutely essential for an observer to protect the eyes against injury by the intense brilliance of the Sun. This phase should never be viewed directly except through strong filters, a dark smoked glass, or a heavily fogged photographic plate or film.

When totality is imminent and only a small crescent of the Sun remains, so-called shadow bands can often be seen on plain light-coloured surfaces, such as floors and walls. These are striations of light and shade, moving and undulating, several centimetres wide. Their speed and direction depend on air currents at various heights, because they are caused by refraction of sunlight by small inhomogeneities in Earth's atmosphere. The phenomenon is similar to the images of water waves seen on the bottom of a sunlit swimming pool or bath.

Eclipses of the Sun
An eclipse of the Sun takes place when the Moon comes between Earth and the Sun so that the Moon's shadow sweeps over the face of Earth ( see the figure of a total solar eclipse). This shadow consists of two parts: the umbra, a cone into which no direct sunlight penetrates; and the penumbra, which is reached by light from only a part of the Sun's disk.

To an observer within the umbra, the Sun's disk appears completely covered by the disk of the Moon; such an eclipse is called total ( see the video). To an observer within the penumbra, the Moon's disk appears projected against the Sun's disk so as to overlap it partly; the eclipse is then called partial for that observer. The umbral cone is narrow at the distance of Earth, and a total eclipse is observable only within the narrow strip of land or sea over which the umbra passes. A partial eclipse may be seen from places within the large area covered by the penumbra. Sometimes Earth intercepts the penumbra of the Moon but is missed by its umbra; only a partial eclipse of the Sun is then observed anywhere on Earth.

By a remarkable coincidence, the sizes and distances of the Sun and Moon are such that they appear as very nearly the same angular size (about 0.5°) at Earth, but their apparent sizes depend on their distances from Earth. Earth revolves around the Sun in an elliptical orbit, so that the distance of the Sun changes slightly during a year, with a correspondingly small change in the apparent size, the angular diameter, of the solar disk. In a similar way, the apparent size of the Moon's disk changes somewhat during the month because the Moon's orbit is also elliptical. When the Sun is nearest to Earth and the Moon is at its greatest distance, the apparent disk of the Moon is smaller than that of the Sun. If an eclipse of the Sun occurs at this time, the Moon's disk passing over the Sun's disk cannot cover it completely but will leave the rim of the Sun visible all around it. Such an eclipse is said to be annular. Total and annular eclipses are called central.

In a partial eclipse ( see the bottom portion of the figure), the centre of the Moon's disk does not pass across the centre of the Sun's. After the first contact, the visible crescent of the Sun decreases in width until the centres of the two disks reach their closest approach. This is the moment of maximum phase, and the extent is measured by the ratio between the smallest width of the crescent and the diameter of the Sun. After maximum phase, the crescent of the Sun widens again until the Moon passes out of the Sun's disk at the last contact.

Eclipses of the Moon
When the Moon moves through the shadow of Earth ( see the figure of a lunar eclipse), it dims considerably but remains faintly visible. Because the shadow of Earth is directed away from the Sun, a lunar eclipse can occur only at the time of the full moon-that is, when the Moon is on the side of Earth opposite to that of the Sun. A lunar eclipse appears much the same at all points of Earth from which it can be seen. When the Moon enters the penumbra, a penumbral eclipse occurs. The dimming of the Moon's illumination by the penumbra is so slight as to be scarcely noticeable, and penumbral eclipses are rarely watched. After a part of the Moon's surface is in the umbra and thus darkened, the Moon is said to be in partial eclipse. After about an hour, when the whole disk of the Moon is within the umbra, the eclipse becomes total ( see video). If the Moon's path leads through the centre of the umbra, the total eclipse can be expected to last about an hour and three-quarters.

Eclipses, occultations, and transits of satellites and other objects
These phenomena as they apply to the natural satellites of planets are conveniently illustrated by the four largest (Galilean) satellites of Jupiter, whose eclipses provide a frequently occurring and fascinating spectacle to the telescopic observer. The three innermost moons ( Io, Europa, and Ganymede) disappear into the shadow of Jupiter at each revolution, though the fourth ( Callisto) is not eclipsed every time. Because of the sizable dimensions of these bodies, some minutes elapse between first contact with the shadow and totality. The orbits of the Galilean moons lie nearly in the same plane as Jupiter's orbit around the Sun, and, at practically every revolution of each moon, the following four eclipse phenomena take place: (1) eclipse of the moon when it passes through Jupiter's shadow, (2) occultation of the moon when it disappears behind the planet, as seen from Earth, (3) transit of the moon across the disk of Jupiter, and (4) transit of the shadow of the moon across the planet's disk.

Historically, the eclipses of Jupiter's Galilean moons are important, for they provided one of the earliest proofs of the finite speed of light. It is possible to calculate with considerable precision the times of disappearance and reappearance of a moon undergoing eclipse. In 1676 the Danish astronomer Ole Rømer, upon noting discrepancies between the observed and calculated times of such eclipses, correctly explained them as being due to the difference in the travel time of light when Earth is nearest to Jupiter or farther away from it.

An event related to the occultation of a planet's moons is the occultation of a space probe by a planet, as observed from Earth. During the beginning and the end of such occultations, radio signals sent out by the spacecraft pass through the planet's atmosphere and travel to Earth. When the signals are received and analyzed, they can provide information about atmospheric density, temperature, and composition. (For examples of the application of this technique, see Saturn: The atmosphere; Uranus: The atmosphere.)

A solar eclipse, especially a total one, can be seen from only a limited part of Earth, whereas the eclipsed Moon can be seen at the time of the eclipse wherever the Moon is above the horizon.

In most calendar years there are two lunar eclipses; in some years one or three or none occur. Solar eclipses occur two to five times a year, five being exceptional; there last were five in 1935, and there will not be five again until 2206. The average number of total solar eclipses in a century is 66 for Earth as a whole.

Numbers of solar eclipses that have taken place or are predicted to take place during the 20th to 25th centuries are:

1901-2000: 228 eclipses, of which 145 were central (i.e., total or annular);

2001-2100: 224 eclipses, 144 central;

2101-2200: 235 eclipses, 151 central;

2201-2300: 248 eclipses, 156 central;

2301-2400: 248 eclipses, 160 central;

2401-2500: 237 eclipses, 153 central.

Any point on Earth may on the average experience no more than one total solar eclipse in three to four centuries. The situation is quite different for lunar eclipses. An observer remaining at the same place (and granted cloudless skies) could see 19 or 20 lunar eclipses in 18 years. Over that period three or four total eclipses and six or seven partial eclipses may be visible from beginning to end, and five total eclipses and four or five partial eclipses may be at least partially visible. All these numbers can be worked out from the geometry of the eclipses. A total lunar eclipse can last as long as an hour and three-quarters, but for a solar total eclipse maximum duration of totality is only 7 ¹/ ₂ minutes. This difference results from the fact that the Moon's diameter is much smaller than the extension of Earth's shadow at the Moon's distance from Earth, but the Moon can be only a little greater in apparent size than the Sun.

Cycles of eclipses
The eclipses of the Sun and the Moon occur at new moon and full moon, respectively, so that one basic time period involved in the occurrence of eclipses is the synodic month-i.e., the interval between successive new moons, as seen from Earth.

A solar eclipse does not occur at every new moon, nor does a lunar eclipse occur at every full moon, because the Moon's orbital plane is inclined to the ecliptic, the plane of the orbit of Earth around the Sun. The angle between the planes is about 5°; thus, the Moon can pass well above or below the Sun. The line of intersection of the planes is called the line of the nodes, being the two points where the Moon's orbit intersects the ecliptic plane. The ascending node is the point where the Moon crosses the ecliptic from south to north, and the descending node is where it crosses from north to south. The nodes move along the ecliptic from east to west as seen from Earth, completing a revolution in 18.6 years. The Moon's revolution from one node to the same node again (called the draconic month, 27.212220 days) takes somewhat less time than a revolution from new moon to new moon (the synodic month, 29.530589 days). For a solar or lunar eclipse to occur, the Moon has to be near one of the nodes of its orbit. The draconic month is therefore the other basic period of eclipses.

Resonance between these two periods results in an interval called the saros, after which time the Moon and the Sun return very nearly to the same relative positions. The saros was known to the ancient Babylonians. It comprises 223 synodic months-that is, 6,585.321124 days, or 241.9986 draconic months. This latter value is nearly a whole number, so the new moon is in almost the same position (i.e., very near a node) at the beginning and end of a saros. The saros lasts 18 years 11 ¹/ ₃ days or 18 years 10 ¹/ ₃ days if five leap years fall within the period. Thus, there is usually a close resemblance between an eclipse and the one taking place 18 years and 11 days earlier or later. Because the date differs by only about 11 days in the calendar year, the latitudes on Earth of the two eclipses will be about the same, as will the relative apparent sizes of the Sun and Moon. The saros period also comprises 238.992 anomalistic months, again nearly a whole number. In one anomalistic month, the Moon describes its orbit from perigee to perigee, the point at which it is nearest to Earth. Thus, the Moon's distance from Earth is the same after a whole number of anomalistic months and very nearly the same after one saros. The saros period is therefore extremely useful for the prediction of both solar and lunar eclipses.

Because of the extra one-third day (and thus an additional eight hours of Earth's rotation) in the saros, the eclipse recurs each time approximately 120° farther west on the surface of Earth. After three saroses, or 54 years and about a month, the longitude is repeated.

There is a regular shift on Earth to the north or to the south of successive eclipse tracks from one saros to the next. The eclipses occurring when the Moon is near its ascending node shift to the south; those happening when it is near its descending node shift to the north. A saros series of eclipses begins its life at one pole of Earth and ends it at the other. A saros series lasts between 1,226 and 1,550 years and comprises 69 to 87 eclipses. As old series finish, new ones begin; about 42 of these series are in progress at any given time.

Two consecutive saros series are separated by the inex, a period of 29 years minus 20 days-that is, 358 synodic months-after which time the new moon has come from one node to the opposite node. A group of inex periods lasts about 23,000 years, with about 70 groups coexisting at any one time, each group comprising an average of 780 eclipses. All other cycles in eclipses are combinations of the saros and the inex.

Prediction and calculation of solar and lunar eclipses
The problem may be divided into two parts. The first is to find out when an eclipse will occur, the other to determine when and where it will be visible.

For this purpose it is convenient first to consider Earth as fixed and to suppose an observer is looking out from its centre. To this observer, labeled O in the figure of the celestial sphere, the Sun and Moon appear projected on the celestial sphere. While this sphere appears to rotate daily, as measured by the positions of the stars, around the axis PP′ (Earth's axis of rotation), the Sun's disk, S, appears to travel slowly along the great circle EE′ (the ecliptic), making a complete revolution in one year. At the same time, the Moon's disk, M, travels along its own great-circle path, LL′, once during a lunar month. The angular diameters of the Sun's and the Moon's disks, S and M, are each about 0.5° but vary slightly.

Every month, the Moon's disk moving along its path, LL′, will overtake the more slowly moving Sun once, at the moment of the new moon. Usually the Moon's disk will pass above or below the Sun's disk. Overlapping of the two results in an eclipse of the Sun, which can happen only when the new moon occurs at the same time that the Sun is near the ascending node or descending node, [nodeascnd] and [nodedescd], respectively, of the Moon's orbit. Because the nodes are 180° apart, eclipses occur in the so-called eclipse seasons, six months apart.

In the figure of the celestial sphere, the projection of Earth's umbra is shown as a disk, U, at the distance of the Moon's orbit. At that distance the shadow's disk subtends an angle of about 1.4°; its centre is always opposite the Sun's disk and travels along the ecliptic, EE′. A lunar eclipse occurs whenever the shadow's disk overlaps the Moon's disk; this happens only when the shadow's disk is near one of the nodes and the Sun is near the opposite node. The Sun's passage through the lunar nodes is thus the critical time for both solar and lunar eclipses. The plane of the Moon's path, LL′, is not fixed, and its nodes move slowly along the ecliptic in the direction indicated by the arrows, making a complete revolution in about 19 years. The interval between two successive passages of the Sun through one of the nodes is termed an eclipse year, and, since the Moon's node moves so as to meet the advancing Sun, this interval is about 18.6 days less than a tropical (or ordinary) year.

In the figure of the Moon's ascending node, this region is depicted as seen from the centre of the celestial sphere and is shown much enlarged. The node is kept fixed, and the apparent motions of the Sun and the Moon (top portion of the figure) are shown relative to the node. To the observer on Earth at the centre of the sphere, the Sun's disk will travel along the ecliptic, EE′, and the Moon's disk along its designated path, LL′. The Sun is so distant compared with the size of Earth that, from all places on Earth's surface, the Sun is seen nearly in the same position as it would be from the very centre. On the other hand, the Moon is relatively near, and so its projected position on the celestial sphere is different for various places of observation on Earth. In fact, it may be displaced as much as 1° from the position in which it is seen from the centre of Earth. If the radius of the Moon's disk is enlarged by 1°, a "Moon circle," C, is obtained that encloses all possible positions of the Moon's disk seen from anywhere on Earth. Conversely, if any disk of the Moon's size is placed inside this Moon circle, there is a place on Earth from which the Moon is seen in that position.

Accordingly, an eclipse of the Sun occurs somewhere on Earth whenever the Moon overtakes the Sun in such a position that the Moon circle, C, passes over the Sun's disk; when the latter is entirely covered by the Moon circle, the eclipse will be total or annular. From the top portion of the figure of the Moon's ascending node, it is evident that a solar eclipse will take place if a new moon occurs while the Sun moves from position S ₁ to position S ₄. This period is the eclipse season; it starts 19 days before the Sun passes through a lunar node and ends 19 days thereafter. There are two complete eclipse seasons, one at each node, during a calendar year. Because there is a new moon every month, at least one solar eclipse, and occasionally two, occurs during each eclipse season. A fifth solar eclipse during a calendar year is possible because part of a third eclipse season may occur at the beginning of January or at the end of December.

The bottom portion of the figure of the Moon's ascending node illustrates the condition necessary for a lunar eclipse. If a full moon occurs within 13 days of the passage of the Sun though a lunar node-and thus of the Earth's umbral disk, U, through the opposite node-the Moon will be eclipsed. (In the figure the umbral disk passes through the ascending node.) Most eclipse seasons, but not all, will thus also contain a lunar eclipse. When two eclipse seasons and a partial third season fall in a calendar year, there may be three lunar eclipses in that year. Eclipses of the Sun are evidently more frequent than those of the Moon. Solar eclipses, however, can be seen from only a very limited region of Earth, whereas lunar eclipses are visible from an entire hemisphere.

During a solar eclipse the shadow cones-the umbra and penumbra-of the Moon sweep across the face of Earth ( see the figure of an eclipse of the Sun), while, at the same time, Earth is rotating on its axis. Within the narrow area covered by the umbra, the eclipse is total. Within the wider surrounding region covered by the penumbra, the eclipse is partial.

Astronomical ephemerides, or tables, that are published annually for the year ahead provide maps tracing the paths of the more important eclipses in considerable detail, as well as data for accurate calculation of the times of contact at any given observing location on Earth. Calculations are made some years ahead in Terrestrial Time (TT), which is defined by the orbital motion of Earth and the other planets. At the time of the eclipse, the correction is made to Universal Time (UT), which is defined by the rotation of Earth and is not rigorously uniform.

Modern computers make it possible to predict solar eclipses several years ahead with high accuracy. By means of the same calculational methods, eclipses can be "predicted backward" in time. The generation of the times and observational locations for ancient eclipses has been valuable in historical and scientific research ( see below Eclipses in history).

Solar research
During a total solar eclipse, when the Moon has fully covered the Sun's brilliant visible disk, the faint extensive outer atmosphere of the Sun, known as the corona, is revealed. Just prior to this event, the chromosphere, a thin bright red layer in the lower solar atmosphere, appears for a few seconds at the edge of the Sun's disk. Then, as the chromosphere vanishes, the corona leaps into view. Pearly white coronal streamers can be seen far beyond the Moon's dark disk, sometimes to a distance several times the Sun's radius. When the corona is made visible, astronomers can observe and record its details.

Because the corona is a million times fainter than the disk of the Sun, it cannot be seen unaided in broad daylight. In 1930 the French astronomer Bernard Lyot invented the coronagraph, a specialized telescope that produces an artificial eclipse of the Sun. Astronomers could then study the corona any day when the aureole, the bright ring around the Sun composed of light scattered by particles in the Earth's atmosphere, was not especially bright. Nevertheless, the daytime sky near the Sun is at least a thousand times darker during a total eclipse than otherwise. Therefore, total eclipses continued to provide the best opportunities to study the Sun's outer atmosphere until the mid-1970s, when suborbital rocket and satellite observatories became available.

Observatories in space have several important advantages over surface-based instruments, being immune to weather and bright skies and above the distorting and filtering effects of Earth's atmosphere. On the other hand, they are exceedingly expensive and require years of development and construction. In comparison, an eclipse expedition-the establishment of a temporary observation station in the path of totality of an upcoming eclipse-is relatively cheap and highly flexible in design. Therefore, despite their limitations, surface-based observations of total solar eclipses continue to play a role in gathering new knowledge about the Sun.

Among the many important advances that were made during past total eclipses, three notable ones can serve as examples-the discovery of the element helium, experimental support for the general theory of relativity, and the discovery that the Sun's corona is exceedingly hot.

Discovery of helium
In 1868, while observing an eclipse whose path of totality passed over India, the French astronomer Pierre Janssen observed a bright yellow line in the spectrum of a solar prominence, a bright cloud of hot ionized gas that extends into the corona. Janssen noticed that the yellow line's wavelength was slightly shorter than that of the well-known line of sodium, and he reported his result to the British astronomer Joseph Norman Lockyer, who had missed the eclipse. Lockyer, using a powerful new spectrograph at the University of Cambridge, was able to observe the yellow line in a prominence outside a solar eclipse. Despite many attempts, he failed to identify the line with any element known on Earth and finally concluded that it corresponded to a new element, which he named helium, from the Greek word for sun. Helium was not discovered on Earth until 1895.

Support for the general theory of relativity
Soon after Albert Einstein's general theory of relativity was published in 1916, scientists set to conducting a number of experimental tests to verify or disprove various predictions of the theory. One prediction was that the dark (absorption) lines known as Fraunhofer lines in the spectrum of sunlight should be redshifted (i.e., shifted toward longer wavelengths) by a precise amount because of the Sun's gravitational field. Astronomers failed initially to find this shift, so in 1918 the validity of the general theory was still in some doubt.

The general theory also predicted that a ray of light emanating from a distant star and passing near the Sun should be deflected a measurable amount by the Sun's gravity. If the ray just grazes the edge of the Sun, the angular deflection should be 1.75 arc seconds, and the deflection should decrease in proportion to the distance of the ray from the Sun's edge. (For comparison, the average solar diameter is 1,922 arc seconds.) Einstein suggested that astronomers should observe this effect at a total eclipse as another test of his theory.

British astronomers, including Arthur Eddington, took up the challenge. They organized two expeditions to observe the five minutes of totality afforded by the eclipse of May 29, 1919, one in Sobral, Brazil, and the other on the island of Príncipe, off the African coast. From Sobral the astronomers obtained a series of photographs on glass plates of the stars around the Sun at mid-totality. The expedition also photographed the same stars that had appeared during the eclipse but without the presence of the Sun. By comparing the relative positions of the stars on the two sets of plates, the astronomers obtained a figure of 1.98 arc seconds for the deflection of starlight at the edge of the solar disk. The expedition to Príncipe, led by Eddington, encountered clouds during the eclipse and was able to photograph only four stars on five plates. From these, Eddington derived an estimate of 1.61 arc seconds for the deflection at the edge of the Sun. The combined results from the two expeditions were close enough to the predicted 1.75 arc seconds to lend support to Einstein's theory but not to establish it unconditionally. Nevertheless, they had tremendous popular appeal and helped establish Einstein as one of the foremost physicists of his time.

Many attempts were made to improve on the accuracy of this stellar method, but with limited success. In 1974, however, astronomers at the U.S. National Radio Astronomy Observatory observed three quasar s that lie in a straight line in the sky and are occulted by the Sun at some time during the year. The radiation from these radio sources was deflected by the Sun in the same manner as starlight. Their radio interferometer was capable of much higher angular precision than photography allows, and their final result was within 1 percent of the prediction of the general theory.

Temperature of the corona
About 1930 German astronomer Walter Grotrian examined spectra of the solar corona he had obtained at a total eclipse. He noticed that, although coronal light had the same distribution of colours as light from the solar surface-the photosphere -it lacked the absorption lines observed in photospheric light. Grotrian hypothesized that coronal light consists of photospheric light that has been scattered toward Earth by free electrons in the corona. To account for the lack of absorption lines in coronal light, these free electrons had to be moving at very high speeds; that is, the corona must be very hot.

A second clue came from some strange bright lines in the corona's spectrum. Because similar lines found in the spectra of interstellar gaseous nebulae ( see nebula) had been shown to be emitted by ionized oxygen and nitrogen under conditions of extremely low gas density and high temperature, Grotrian speculated that the bright coronal lines might have a similar origin. He wrote to Bengt Edlén, a Swedish physicist who was studying the spectra of elements at very high temperatures. With atomic data that Edlén supplied, Grotrian was able to predict the wavelengths of two of the strongest coronal lines, including one that can be produced only from ionized iron at a temperature of about a million kelvins (K). With Grotrian thus showing the way, Edlén eventually was able to identify the majority of the two dozen known coronal lines with terrestrial elements such as silicon, calcium, and iron. All these lines are emitted only at temperatures of a million K or more. They are called "forbidden" because, according to the rules of quantum mechanics, the atomic transitions from higher to lower energy states responsible for lines have only a small likelihood of occurring under normal laboratory conditions.

Since Grotrian's and Edlén's work, astronomers have learned that some parts of the normal corona can attain temperatures as high as three or four million K. In comparison, the photosphere has a temperature of only 6,000 K. Because heat cannot flow spontaneously from cooler to hotter regions, some unknown, nonthermal process must maintain the high temperature of the corona. Although astronomers have searched for this process for decades, they have yet to identify it positively. Many investigations of the corona still take place during the ideal conditions of a total solar eclipse.

Lunar research
Lunar eclipses can yield information about the cooling of the Moon's soil when the Sun's radiation is suddenly removed and therefore about the soil's conductivity of heat and its structure. Infrared and radio-wavelength radiation from the Moon declines in intensity more slowly than does visible light emission during an eclipse because they are emitted from below the surface, and measurements indicate how far the different kinds of radiation penetrate into the lunar soil. Infrared observations show that at many "bright spots" the soil retains its heat much longer than in surrounding areas.

Because of the absence of a lunar atmosphere, the Moon's solid surface is exposed to the full intensity of ultraviolet and particulate radiation from the Sun, which may give rise to fluorescence in some rock materials. Observations during lunar eclipses have given positive results for this phenomenon, with the appearance of abnormal bright regions in eclipse-obscured parts of the Moon.

A transit of Mercury or Venus across the face of the Sun, as seen from Earth, occurs at inferior conjunction, when the planet lies between the Sun and Earth. Because the orbits of both planets, like the Moon's orbit, are inclined to the ecliptic, these planets usually pass above or below the Sun ( see above Cycles of eclipses). Also like the Moon's orbit, each planet's orbit intersects the ecliptic plane in two points called nodes; if inferior conjunction occurs at a time when the planet is near a node, a transit of the Sun can occur.

For Mercury these times occur around May 8 and November 10. November transits occur at intervals of 7, 13, or 33 years, while May transits occur only at the latter two intervals. On average, Mercury transits the Sun about 13 times per century. In the transit of Mercury that took place on November 15, 1999, the planet just grazed the edge of the Sun. The Transition Region and Coronal Explorer (TRACE) satellite, an Earth-orbiting solar observatory launched in 1998, recorded the event in several wavelengths ( see the photo). Mercury's dark disk measured only about 10 arc seconds in diameter, compared with the Sun's diameter of 1,922 arc seconds. Recent transits of Mercury occurred on May 7, 2003, and November 8, 2006, and the next will occur on May 9, 2016, November 11, 2019, and November 13, 2032. Observers cannot see Mercury's tiny disk against the Sun without some form of magnification.

Transits of Venus occur at its nodes in December and June and generally follow a recurrence pattern of 8, 121, 8, and 105 years before starting over. Following the transits of December 9, 1874, and December 6, 1882, the world waited 121 years until June 8, 2004, for the next transit to occur and then 8 years for the next on June 5-6, 2012. The next transits will occur on December 11, 2117, and December 8, 2125. Unlike a transit of Mercury, a transit of Venus can be watched without magnification through a suitable dark filter or as an image projected on a screen through a pinhole lens.

Observing the transits of Venus was of great importance to 18th- and 19th-century astronomers, because careful timings of the events permitted accurate measurement of the distance between Venus and Earth. This distance in turn allowed calculation of the distance between Earth and the Sun, called the astronomical unit, as well as the distances to the Sun of all the other planets. For more-detailed discussions of this topic, see astronomical unit; Venus: Observations from Earth.

The Moon occults all the objects in the sky in a 10°-wide belt centred on the ecliptic within a period of about nine years. Initially, astronomers' primary goal of observing lunar occultations of stars was to refine the parameters of the Moon's orbit. With the advent of large telescopes and fast electronics, lunar occultations have found application in measuring stellar angular diameters, detecting dust envelopes around stars, and a variety of other studies.

Lunar occultations are used extensively to determine the angular diameters of cool giant stars such as Antares and Aldebaran. An angular resolution of a few thousandths of an arc second is achievable. As a star becomes occulted, its light is diffracted around the sharp edge of the Moon and produces a characteristic oscillatory signal. From the duration and shape of the signal, astronomers can derive the diameter and effective surface temperature of the star. The event is so fast, lasting only a few milliseconds, that any distortion due to Earth's atmosphere (twinkling, or scintillation) is eliminated, which is an advantage over the alternative method of optical interferometry. The diameters of some stars determined in this way seem to vary in time, as if the stars are pulsating slowly.

Lunar occultations have also revealed dust shells around stars and helped determine their shape and structure. One class of stars studied this way are the Wolf-Rayet stars-large, massive stars that blow off a thick envelope of material from their surface in a stellar wind as they near the end of their lives. In addition, lunar occultations are useful for discovering binary stars, and systematic surveys of the sky are made for this purpose.

Arguably the most famous application of lunar occultation occurred in 1962, when the British astronomer Cyril Hazard and colleagues used the Parkes radio telescope in Australia to refine measurements of the positions in the sky of catalogued radio sources that were not identified with any known stars or galaxies. To improve the accuracy of the positions, Hazard timed the occultation of the sources by the Moon. One radio source, designated 3C 273, turned out to consist of two sources separated by 19.5 arc seconds. The signal from one component suggested it could be a star, but it had a type of radio spectrum that had never been seen before. The following year the American astronomer Maarten Schmidt identified a 12th-magnitude star at the precise location of this radio source and obtained its spectrum. The spectrum showed that the source was receding at 15 percent of the speed of light and was therefore very distant. Hazard had in fact resolved the location of the first known quasi-stellar radio source, or quasar.

All the major planets and their moons occult stars in their paths, and such occultations can occasionally yield information on planetary atmospheres. For example, variations over time in the atmosphere of Pluto have been inferred from stellar occultations. Sometimes a stellar occultation produces a stunning surprise, as occurred on March 10, 1977, when the planet Uranus was predicted to pass between Earth and a bright star. The event was observed by several teams of astronomers, who hoped to derive an accurate estimate of the diameter of the planet from their data. Unexpectedly, however, the light from the star was briefly obscured several times before and after the disk of Uranus occulted it. It was concluded that the brief changes in the star's brightness were due to the presence around Uranus of a previously unobserved system of rings, somewhat like the rings of Saturn.

Asteroids, like moons and planets, occult stars as they orbit the Sun. By timing the vanishing and reappearance of a star as an asteroid crosses it from two or more locations on Earth, astronomers can determine the asteroid's size and shape. In modern times a large community of professional and amateur scientists has cooperated in predicting and observing such occultations. For example, on January 19, 1991, observers at nine locations across the United States timed the occultation of a star by Kleopatra, a main-belt asteroid. The timings determined nine different chords across the asteroid, from which was drawn a rough outline of the asteroid, showing it to have an elongated, cigar shape.

Astronomers have estimated that more than half of all stars in the Milky Way Galaxy are members of a double or a more complex multiple star system. Most of these are too far from Earth for the individual stars to be resolved. In a double star, or binary, system ( see binary star), each star attracts the other gravitationally and orbits about a unique point, the centre of mass of the pair. If the plane of their orbits lies edge-on toward Earth, each star will be seen to eclipse the other once each orbital period. Such a system is known as an eclipsing binary.

In an eclipsing binary system, the total amount of light varies periodically; for this reason it is alternatively called an eclipsing variable star. The light curve of an eclipsing binary-i.e., a plot of its changes in brightness over time-has a deep minimum when the brighter star is eclipsed and a shallower minimum when the dimmer star is eclipsed. The variable star Algol, or Beta Persei, was the first eclipsing binary to be recognized as such.

Eclipsing binaries are the principal sources of information on the masses and radii of stars. A complete analysis of the light curve can yield the radii of the stars (in units of their separation); orbital characteristics such as eccentricity, orientation in space, and tilt with respect to Earth; and even the surface temperatures of the stars. Kepler's third law relates the orbital period, the separation of the stars, and the sum of their masses. From observations of the periodic shifts of each star's spectral lines due to motion of the star toward or away from Earth (the Doppler effect), astronomers can determine the velocity along the line of sight of each star in its orbit. The ratio of the stellar masses then follows from their velocities. With the sum and ratio of the masses in hand, both masses can be determined.

Studies of eclipsing binaries have revealed unexpected structural details and time-related changes in the component stars. Some stars turn out to have dark starspots, for example, similar to but much larger than sunspots on the Sun. Other stars flare in brightness as mass is exchanged from one component to the other. Rapid rotation of some stars flattens their shapes into ellipsoids. Even the long-known solar phenomenon of limb darkening, the gradual decrease in brightness from the centre to the edge of the Sun's disk, has been detected in the component stars of eclipsing binaries.

Zeta Aurigae is the prototype of a class of eclipsing binaries composed of a cool supergiant star and a hot blue star. Although the supergiant's atmosphere is large enough to reach to the orbit of Venus were the star to replace the Sun in the solar system, it is very rarefied. When the blue star first passes behind the supergiant, its light is not fully extinguished but travels through the supergiant's cool atmosphere, which modifies the light's characteristics. Thus, the blue star acts as a probe of the supergiant's atmosphere. By analyzing the combined spectra of the two stars, astronomers can determine the temperature, density, and composition of the supergiant's atmosphere.

Beta Lyrae is the prototype of another class of eclipsing binaries, in which one star is embedded in a ring or disk of material that it has pulled off the other star. One star has twice the mass of the Sun; the companion star is much dimmer, though it has a mass of about 12 Suns. This binary is highly variable, and it shows signs that mass is spiraling from one star to the other at a rate of about five Earth masses per year. This exchange of mass has apparently caused an increase in the orbital period, from 12.89 days in 1784, when it was discovered, to 12.94 days in 1978.

Jack B. Zirker

Jakob Houtgast

Eclipses of the Sun and Moon are often quite spectacular, and in ancient and medieval times they were frequently recorded as portents-usually of disaster. Hence, it is not surprising that many of these events are mentioned in history and literature as well as in astronomical writings.

Well over 1,000 individual eclipse records are extant from various parts of the ancient and medieval world. Most known ancient observations of these phenomena originate from only three countries: China, Babylonia, and Greece. No eclipse records appear to have survived from ancient Egypt or India, for example. Whereas virtually all Babylonian accounts are confined to astronomical treatises, those from China and Greece are found in historical and literary works as well. However, the earliest reliable observation is from Ugarit of a total solar eclipse that happened on March 3, 1223 bce. The first Assyrian record dates from much later, June 15, 763 bce. From then on, numerous Babylonian and Chinese observations are preserved. Eclipses are occasionally noted in surviving European writings from the Dark Ages (for instance, in the works of the 5th-century bishop Hydatius and the 8th-century theologian and historian St. Bede the Venerable). However, during this period only the Chinese continued to observe and report such events on a regular basis. Chinese records in the traditional style continued almost uninterrupted to modern times.

Many eclipses were carefully recorded by the astronomers of Baghdad and Cairo between about 800 and 1000 ce. Also after about 800, both European and Arabic annalists began to include in their chronicles accounts of eclipses and other remarkable celestial phenomena. Some of these chronicles continued until the 16th century and even later, although the peak period was between about 1100 and 1400. About 1450, European astronomers commenced making fairly accurate measurements of the time of day or night when eclipses occurred, and this pursuit spread rapidly following the invention of the telescope. This discussion is confined to eclipse observations made in the pretelescopic period.

The present-day value of ancient and medieval records of eclipses falls into two main categories: (1) chronological, depending mainly on the connection between an eclipse and a significant historical event, and (2) astronomical, especially the study of long-term variations in the length of the mean solar day.

The Sun is usually so brilliant that the casual observer is liable to overlook those eclipses in which less than about 80 percent of the solar disk is obscured. Only when a substantial proportion of the Sun is covered by the Moon does the loss of daylight become noticeable. Hence, it is rare to find references to small partial eclipses in literary and historical works. At various times, astronomers in Babylonia, China, and the Arab lands systematically reported eclipses of small magnitude, but their vigilance was assisted by their ability to make approximate predictions. They thus knew roughly when to scrutinize the Sun. Arab astronomers sometimes viewed the Sun by reflection in water to diminish its brightness when watching for eclipses. The Roman philosopher and writer Seneca (c. 4 bce-65 ce), on the other hand, recounts that, in his time, pitch was employed for this purpose. It is not known, however, whether such artificial aids were used regularly.

When the Moon covers a large proportion of the Sun, the sky becomes appreciably darker, and stars may appear. On those rare occasions when the whole of the Sun is obscured, the sudden occurrence of intense darkness, accompanied by a pronounced fall in temperature, may leave a profound impression on eyewitnesses. Total or near-total eclipses of the Sun are of special chronological importance. On average, they occur so infrequently at any particular location that if the date of such an event can be established by historical means to within a decade or two, it may well prove possible to fix an exact date by astronomical calculation.

The Moon even when full is much dimmer than the Sun, and lunar eclipses of quite small magnitude are thus fairly readily visible to the unaided eye. Both partial and total obscurations are recorded in history with roughly comparable frequency. As total eclipses of the Moon occur rather often (every two or three years on average at a given place), they are of less chronological importance than their solar counterparts. There are, however, several notable exceptions, as is discussed below.

Literary and historical references

According to long-established tradition, the history of astronomy in ancient China can be traced back before 2000 bce. The earliest relics that are of astronomical significance date from nearly a millennium later, however. The Anyang oracle bones (inscribed turtle shells, ox bones, and so forth) of the latter part of the Shang dynasty (c. 1600-1046 bce), which were uncovered near Anyang in northeastern China, record several eclipses of both the Sun and the Moon. The following report is an example:

On day guiyou [the 10th day of the 60-day cycle], it was inquired [by divination]: "The Sun was eclipsed in the evening; is it good?" On day guiyou it was inquired: "The Sun was eclipsed in the evening; is it bad?"

The above text provides clear evidence that eclipses were regarded as omens at this early period (as is true of other celestial phenomena). Such a belief was extremely prevalent in China during later centuries. The term translated here as "eclipse" ( shi) is the same as the word for "eat." Evidently the Shang people thought that a monster actually devoured the Sun or Moon during an eclipse. Not until many centuries later was the true explanation known, but by then the use of the term shi was firmly established to describe eclipses, and so it remained throughout Chinese history. The oracle-bone text, translated above, twice gives the day of the sexagenary cycle; this cycle, which was independent of any astronomical parameter, continued in use (seemingly without interruption) until modern times. Nevertheless, as the year in which an eclipse occurred is never mentioned on the preserved oracle bones (many of which are mere fragments), dating of these observations by astronomical calculation has proved extremely difficult. In general, Shang chronology is still very uncertain.

The ("Classic of Poetry") contains a lamentation occasioned by an eclipse of the Moon followed by an eclipse of the Sun. The text, dating from the 8th century bce, may be translated:

The Sun was eclipsed, we found it greatly ominous...that this Moon is eclipsed is but an ordinary matter; but that this Sun is eclipsed-wherein lies the evil?

The different attitudes toward solar and lunar eclipses at this time is interesting. Throughout the subsequent 1,000 years or so, lunar eclipses were hardly ever reported in China-in marked contrast to solar obscurations, which were systematically observed during much of this period. The earliest of these observations are recorded in a chronicle of the Chinese state of Lu (now in Shandong province), the birthplace of Confucius. This work, known as the ("Spring and Autumn [Annals]"), lists many solar eclipses between 722 and 481 bce. On three occasions the Chunqiu describes eclipse ceremonies in which drums were beaten and oxen were sacrificed. Further, three eclipses (occurring in 709, 601, and 549 bce) were described as total. The earliest of these, that of July 17, 709 bce, is recorded as follows:

Third year of Duke Huan, 7th month, day renchen [the 29th day of the cycle], the first day of the month. The Sun was eclipsed and it was total.

Computation shows that this eclipse was indeed total at Qufu, the Lu capital.

From about 200 bce (following the unification of China into a single empire), a wide variety of celestial phenomena began to be noted on a regular basis. Summaries of these records are found in astronomical treatises contained in the official histories. In many instances, a report is accompanied by a detailed astrological prognostication. For example, the Houhanshu ("History of the Later Han Dynasty") contains the following account under a year corresponding to 119-120 ce:

On the day wuwu [the 55th cyclical day], the 1st day of the 12th lunar month, the Sun was eclipsed; it was almost complete. On the Earth it became like evening. It was 11 deg in the constellation of the Maid. The woman ruler [i.e., the empress dowager] showed aversion to it. Two years and three months later, Deng, the empress dowager, died.

The date of this eclipse is equivalent to January 18, 120. On this exact day there occurred an eclipse of the Sun that was very large in China. The above-cited text is particularly interesting because it clearly describes an obscuration of the Sun, which, though causing dusk conditions, was not quite total where it was seen. With regard to the accompanying prognostication, it should be pointed out that a delay of two or three years between the occurrence of a celestial omen and its presumed fulfillment is quite typical of Chinese astrology.

Systematic observation of lunar eclipses in China began about 400 ce, and from this period onward the official astronomers often timed the various phases of both solar and lunar eclipses with the aid of clepsydra s (water clocks). Chinese astronomical techniques spread to Korea and Japan, and, especially after 1000 ce, eclipses were regularly observed independently in all three countries. However, the Chinese records are usually the most detailed.

The following account from the Yuanshi ("History of the Yuan Dynasty") of the total lunar eclipse of May 19, 1277, follows the customary practice of quoting timings in double hours (12 to a combined day and night) and marks (each equal to ¹/ ₁₀₀ of a day and night, or 0.24 hour):

14th year of the Zhiyuan reign period, 4th month, day guiyou [the 10th cyclical day], full Moon. The Moon was eclipsed. Beginning of loss at 6 marks in the hour of zi; the eclipse was total at 3 marks in the hour of chou; maximum at 5 marks in the hour of chou; reappearance of light at 7 marks in the hour of chou; restoration to fullness at 4 marks in the hour of yin.

The three consecutive double hours zi, chou, and yin correspond, respectively, to 11 pm to 1 am, 1 am to 3 am, and 3 am to 5 am. The measured times are equivalent to 12:34 am (start of eclipse), 1:50 am (beginning of totality), 2:19 am (mid-eclipse), 2:48 am (end of totality), and 4:05 am (end of eclipse).

From the 3rd century ce onward, there is evidence of attempts at predicting eclipses by Chinese astronomers. Crude at first, these predictions reached their peak accuracy near the end of the 13th century, with typical timing errors of about one-fourth of an hour.

The Assyrian Chronicle, a cuneiform tablet that preserves the names of the annual magistrates who gave their names to the years (similar to the later Athenian archons or Roman consuls), records under the year that corresponds to 763-762 bce: "Revolt in the citadel; in [the month] Siwan [equivalent to May-June], the Sun had an eclipse." The reference must be to the eclipse of June 15, 763 bce, the only large eclipse visible in Assyria over a period of many years. A possible allusion to the same eclipse is found in the Bible: " 'And on that day,' says the Lord God, 'I will make the Sun go down at noon, and darken the earth in broad daylight' " (Amos 8:9). Amos was prophesying during the reign of King Jeroboam II (786-746 bce) of Israel, and the eclipse would be very large throughout Israel.

Many references to both solar and lunar eclipses in the first half of the 7th century bce are found among the divination reports to Assyrian kings. These tablets, which are now largely in the British Museum, were found in the royal archives at Nineveh. A text probably dating from 675 bce carries the following account, indicating that the eclipse was regarded as an unfavourable omen:

The eclipse of the Moon which took place in Marchesvan [month VIII] began [in the east]. That is bad for Subartu. What [is wrong]? After it, Jupiter ent[ered] the Moon three times. What is being done to make its evil pass?

Babylonian
Until the discovery of the late Babylonian astronomical texts in the latter half of the 19th century, the Alexandrian astronomer Ptolemy's Almagest (2nd century ce) was the only source of Babylonian eclipse observations. Ptolemy cites several records of lunar eclipses, the earliest in 721 bce. Unfortunately, the dates and observational details are not in original form but have been edited, presumably by the Greek astronomer Hipparchus (2nd century bce). Dates have been converted to the Egyptian 365-day calendar, while times have been expressed in hours instead of the original units.

The discovery and decipherment of vast numbers of cuneiform astronomical texts at the site of Babylon in the 1870s and '80s completely revolutionized the study of Babylonian astronomy. Most of the extant texts, dating from about 747 bce to 75 ce, are in the British Museum. Numerous day-to-day astronomical diaries contain records of celestial phenomena, including many eclipses. Although most of the tablets are very fragmentary, additional Babylonian collections of eclipse reports-abstracted from the original diaries-also survive. An example of a lunar eclipse record, dating from 80 bce, is as follows. Time intervals, presumably measured with the aid of a water clock, are expressed in UŠ (time-degrees, equal to four minutes), while eclipse magnitudes are expressed in "fingers," each equal to ¹/ ₁₂ of the lunar diameter:

Year 168 [ Arsacid dynasty], that is year 232 [ Seleucid kingdom]...month I, day 13...lunar eclipse.... In 20 deg of night it made six fingers. Duration of maximal phase 7 deg of night, until it began to become bright. In 13 deg...4 fingers lacking to brightness it set.... [Began] at 40 deg before sunrise.

The date, when converted to the Julian calendar (April 11, 80 bce), is exactly correct. Sunrise on this occasion would occur at 5:37 am, so that the measured start of the eclipse was at 2:57 am, and maximum phase (when half of the Moon was estimated to be in shadow) was at 4:31 am. When the Moon set, one-third of its disk was observed to be still in shadow. Use of "fingers" to express the magnitude of an eclipse (both lunar and solar) spread to Greece and hence to the Arab world. This convention was still fairly standard among astronomers worldwide until the 20th century.

Babylonian eclipse predictions, which were based on past series of observations, were fairly accurate for this early period. Timing errors averaged about two hours, and predictions gave a useful indication of the likelihood of an eclipse to intending observers.

In his Antiquities of the Jews, the Jewish historian Flavius Josephus says the Judean king Herod died in the spring shortly after a lunar eclipse. Calculation shows that the only springtime lunar eclipses visible in Israel between 17 bce and 3 ce took place on March 23, 5 bce, and March 13, 4 bce. The former was total in the mid-evening, while on the latter occasion about one-third of the Moon was in shadow around 3 am. These two dates are conveniently close to one another, although the latter date is usually preferred by chronologists-implying that Herod died in the spring of 4 bce.

In a fragment of a lost poem by the 7th-century-bce Greek poet Archilochus occur the words:

Nothing can be surprising any more or impossible or miraculous, now that Zeus, father of the Olympians, has made night out of noonday, hiding the bright sunlight, and fear has come upon mankind. After this, men can believe anything, expect anything.

This seems a clear reference to a total solar eclipse. The phenomenon has been identified as most likely the eclipse of April 6, 648 bce, which was total in the Aegean and occurred during Archilochus's lifetime.

Fragments survive of other early Greek poetic descriptions of eclipses, and the ninth paean of Pindar, addressed to the Thebans, takes an eclipse of the Sun as its theme:

Beam of the Sun! O thou that seest from afar, what wilt thou be devising? O mother of mine eyes! O star supreme, reft from us in the daytime! Why hast thou perplexed the power of man and the way of wisdom, by rushing forth on a darksome track?

The 5th-century-bce poet then proceeds to speculate on the meaning of this omen. Although he prays, "Change this worldwide portent into some painless blessing for Thebes," he adds, "I in no wise lament whate'er I shall suffer with the rest." This strongly suggests that Pindar, who was a Theban, had himself recently witnessed a great eclipse at his hometown. The most probable date for the eclipse is April 30, 463 bce; modern calculations indicate that the eclipse was nearly total at Thebes.

The historian Thucydides records three eclipses during the Peloponnesian War, which began in 431 bce and lasted for 27 years. The first of these was a solar obscuration that occurred in the summer of the first year of the war (calculated date August 3, 431 bce). On this occasion, the Sun assumed the form of a crescent in the afternoon before returning to its natural shape, and during the eclipse some stars became visible. This description agrees well with modern computations, except that no "star" apart from the planet Venus should have been seen. Seven years afterward Thucydides noted that a "small" solar eclipse took place in the summer of the eighth year of the war (calculated date March 21, 424 bce). Finally, a lunar eclipse occurred in the summer of the 19th year of the war (calculated date August 27, 413 bce). This last date had been selected by the Athenian commanders Nicias and Demosthenes for the departure of their armies from Syracuse. All preparations were ready, but the signal had not been given when the Moon was totally eclipsed in the evening. The Athenian soldiers and sailors clamoured against departure, and Nicias, in obedience to the soothsayers, resolved to remain thrice nine days. This delay enabled the Syracusans to capture or destroy the whole of the Athenian fleet and army.

August 15, 310 bce, is the date of a total eclipse of the Sun that was seen at sea by the tyrant Agathocles and his men after they had escaped from Syracuse and were on their way to Africa. Diodorus Siculus, a historian of the 1st century bce, reported that "on the next day [after the escape] there occurred such an eclipse of the Sun that utter darkness set in and the stars were seen everywhere." Historians of astronomy have often debated whether Agathocles' ships sailed around the north or south coast of Sicily during the course of the journey. Modern computations of the eclipse track are still unable to resolve this issue, although they indicate that the eclipse was total over much of Sicily.

In the dialogue of the Greek author Plutarch (46-c. 119 ce) concerning the features of the Moon's disk, one of the characters, named Lucius, deduces from the phases of the Moon and the phenomenon of eclipses a similarity between Earth and the Moon. Lucius illustrates his argument by means of a recent eclipse of the Sun, which, "beginning just after noonday, made many stars shine out from many parts of the sky and tempered the air in the manner of twilight." This eclipse has been identified with one that occurred on March 20, 71 ce, which was total in Greece. Whether Plutarch is describing a real, and therefore datable, event or is merely basing his description on accounts written by earlier authors has been disputed. However, his description is so vivid and original that it seems likely that Plutarch witnessed the eclipse himself. Later in the same dialogue, Lucius refers to a brightness that appears around the Moon's rim in total eclipses of the Sun. This is one of the earliest known allusions to the solar corona. Plutarch was unusually interested in eclipses, and his Parallel Lives, an account of the deeds and characters of illustrious Greeks and Romans, contains many references to both lunar and solar eclipses of considerable historical importance. There also are frequent records of eclipses in other ancient Greek literature.

Ptolemy in his Almagest records several lunar eclipses between 201 bce and 136 ce. Most of these were observed at Alexandria in Egypt. For instance, the eclipse of May 1, 174 bce, is described in the following words:

From the beginning of the eighth hour till the end of the tenth in Alexandria there was an eclipse of the Moon which reached a maximum obscuration of 7 digits from the north; so mid-eclipse occurred 2 ¹/ ₂ seasonal hours after midnight, which corresponds to 2 ¹/ ₃ equinoctial hours.

The local times of beginning and end correspond to about 12:55 am and 3:35 am, so mid-eclipse would have been close to 2:15 am.

Roman history is less replete with references to eclipses than that of Greece, but there are several interesting allusions to these events in Roman writings. Some, like the total solar eclipse said by Dio Cassius, a Roman historian of the 3rd century ce, to have occurred at the time of the funeral of Julia Agrippina, the mother of the Roman emperor Nero, never took place. An eclipse of the Sun recorded by the historian Livy (64/59 bce-17 ce) in a year corresponding to 190 bce is of interest to students of astronomy and of the Roman calendar alike. Although Livy notes that the event happened in early July, the calculated date is March 14. Consequently, the Roman calendar in that year must have been more than three months out of adjustment.

What may well be an indirect allusion to a total eclipse of the Sun is recorded by Livy for a time corresponding to 188-187 bce (the consulship of Valerius Messala and Livius Salinator during the Roman Republic):

Before the new magistrates departed for their provinces, a three-day period of prayer was proclaimed in the name of the College of Decemvirs at all the street-corner shrines because in the daytime, between about the third and fourth hours, darkness had covered everything.

The darkness took place sometime after the election of the consuls (Ides of March), and, allowing for the confusion of the Roman calendar at this time, the total eclipse of July 17, 188 bce, would be the most satisfactory explanation for the unusual morning darkness. Since the Sun is not mentioned in the text, the phenomenon possibly occurred on a cloudy day.

The total eclipse of the Moon on the evening of June 21, 168 bce, has attracted much attention. This event occurred shortly before the defeat of Perseus, the last king of Macedonia, by the Romans at the Battle of Pydna. The contemporary Greek historian Polybius, in remarking on this eclipse, stated that "the report gained popular credence that it portended the eclipse of a king. This, while it lent fresh courage to the Romans, discouraged the Macedonians." Polybius added the wry comment: "So true is the saying, 'there are many empty things in war.' "

Medieval European
Following the close of the Classical age in Europe, eclipses were in general only rarely recorded by European writers for several centuries. Not until after about 800 ce did eclipses and other celestial phenomena begin to be frequently reported again, especially in monastic chronicles. Hydatius, bishop of Chaves (in Portugal), was one of the few known chroniclers of the early Middle Ages. He seems to have had an unusual interest in eclipses, and he recounted the occurrence of five such events (involving both the Sun and the Moon) between 447 and 464 ce. In each case, only brief details are given, and Hydatius gives the years of occurrence in terms of the Olympiads (i.e., reckoning time from the first Olympic Games, in 776 bce). During the total lunar eclipse of March 2, 462 ce (this date is known to be accurate), the Moon is said to have been "turned into blood." Statements of this kind are common throughout the Middle Ages, presumably inspired by the biblical allusion in Joel (2:31). Similar descriptions, however, are occasionally found in non-Judeo-Christian sources-for example, a Chinese one of 498 ce.

Given below is a selection from the vast number of extant medieval European reports of eclipses. In many cases the date is accurately recorded, but there also are frequent instances of chronological error.

In the year 733 ce the continuation of Bede's Historia ecclesiastica gentis Anglorum ("Ecclesiastical History of the English People") contains an early reference to an annular eclipse on a date corresponding to August 14. When the eclipse was at its height, "almost the whole of the Sun's disk seemed to be like a black and horrid shield." Bede was the first historian to use ad dates systematically.

An occultation of a bright star by the eclipsed Moon in 756 (actually the previous year) is the subject of an entry in the chronicle of Simeon of Durham. Although Simeon lived some four centuries after the event, he is clearly quoting an eyewitness source:

Moreover, the Moon was covered with a blood-red color on the 8th day before the Kalends of December [i.e., November 24] when 15 days old, that is, the Full Moon; and then the darkness gradually decreased and it returned to its original brightness. And remarkably indeed, a bright star following the Moon itself passed through it, and after the return to brightness it preceded the Moon by the same distance as it had followed the Moon before it was obscured.

The text gives no hint of the identity of the star. Modern computations show that the Moon was totally eclipsed on the evening of November 23, 755. During the closing stages of the eclipse, Jupiter would have been occulted by the Moon, as seen from England. This is an example of the care with which an observer who was not an astronomer could describe a compound astronomical event without having any real understanding of what was happening.

Several eclipses are recorded in Byzantine history, beginning in the 6th century. By far the most vivid account relates to the solar eclipse of December 22, 968. This was penned by the contemporary chronicler Leo the Deacon:

At the winter solstice there was an eclipse of the Sun such as has never happened before....It occurred on the 22nd day of the month of December, at the 4th hour of the day, the air being calm. Darkness fell upon the Earth and all the brighter stars revealed themselves. Everyone could see the disk of the Sun without brightness, deprived of light, and a certain dull and feeble glow, like a narrow headband, shining round the extreme parts of the edge of the disk. However, the Sun gradually going past the Moon (for this appeared covering it directly) sent out its original rays, and light filled the Earth again.

This is the earliest account of the solar corona that can be definitely linked to a datable eclipse. Although the appearance of the corona during totality is rather impressive, early descriptions of it are extremely rare. Possibly many ancient and medieval eyewitnesses of total eclipses were so terrified by the onset of sudden darkness that they failed to notice that the darkened Sun was surrounded by a diffuse envelope of light.

In a chronicle of the Norman rule in Sicily and southern Italy during the 11th century, Goffredo Malaterra records an eclipse of the Sun that, even though it caused alarm to some people, was evidently regarded by others as no more than a practical inconvenience:

[1084 ce] On the sixth day of the month of February between the sixth and ninth hours the Sun was obscured for the space of three hours; it was so great that any people who were working indoors could only continue if in the meantime they lit lamps. Indeed some people went from house to house to get lanterns or torches. Many were terrified.

This eclipse actually occurred on February 16, 1086. It was the only large eclipse visible in southern Italy for several years around this time; hence, the chronicler had mistaken both the year and day.

The German astronomer Regiomontanus (Johannes Müller) carefully timed nine eclipses between 1457 and 1471. He compared his measured times with those calculated by using the Alfonsine Tables, a set of astronomical tables compiled two centuries beforehand that allowed computation of eclipses and planetary positions. His account of the lunar eclipse of December 17, 1461, is as follows:

The Moon rose eclipsed by 10 digits of its diameter [calculated]. Indeed I merely noted 8 [digits]. Moreover, from the Alfonsine computations the end of the eclipse occurred at 1 hour and 56 minutes after sunset. At this same end of the eclipse the altitude of the star Alhioth [Capella, or Alpha Aurigae] in the east was 38 degrees 30 minutes, whereas [the altitude of] the star Aldebaran [Alpha Tauri] was 29 degrees in the east. This was in the city of Rome.

In quoting star altitudes, Regiomontanus was following a practice favoured by medieval Arab astronomers ( see below). The local times corresponding to the two altitude measurements are respectively 5:21 pm and 5:25 pm; these compare with the Alfonsine result of 6:30 pm. Hence, the tables were more than an hour in error at this date.

Medieval Islamic
Courtesy of F. Richard Stephenson; in the collection of the Leiden University Library

Like their Christian counterparts, medieval Islamic chroniclers recorded a number of detailed and often vivid descriptions of eclipses. Usually the exact date of occurrence is given (on the lunar calendar). A graphic narrative of the total solar eclipse of June 20, 1061, was recorded by the Baghdad annalist Ibn al-Jawzī, who wrote approximately a century after the event:

On Wednesday, when two nights remained to the completion of the month Jumādā al-Ūlā [in ah 453], two hours after daybreak, the Sun was eclipsed totally. There was darkness and the birds fell whilst flying. The astrologers claimed that one-sixth of the Sun should have remained [uneclipsed] but nothing of it did so. The Sun reappeared after four hours and a fraction. The eclipse was not in the whole of the Sun in places other than Baghdad and its provinces.

The date corresponds exactly to June 20, 1061 ce, on the morning of which there was a total eclipse of the Sun visible in Baghdad. The duration of totality is much exaggerated, but this is common in medieval accounts of eclipses. The phenomenon of birds falling from the sky at the onset of the total phase was also noticed in Europe during several eclipses in the Middle Ages.

Two independent accounts of the total solar eclipse of 1176 are recorded in contemporary Arab history. Ibn al-Athīr, who was age 16 at the time, described the event as follows:

In this year [ah 571] the Sun was eclipsed totally and the Earth was in darkness so that it was like a dark night and the stars appeared. That was the forenoon of Friday the 29th of the month Ramaḍān at Jazīrat Ibn ʿUmar, when I was young and in the company of my arithmetic teacher. When I saw it I was very much afraid; I held on to him and my heart was strengthened. My teacher was learned about the stars and told me, "Now, you will see that all of this will go away," and it went quickly.

The date of the eclipse is given correctly, apart from the weekday (actually Sunday), and is equivalent to April 11, 1176 ce. Calculation shows that the whole of the Sun would have been obscured over a wide region around Jazīrat Ibn ʿUmar (now Cizre, Turkey). Farther south, totality was also witnessed by the Muslim leader Saladin and his army while crossing the Orontes River near Ḥamāh (in present-day Syria). The chronicler ʿImād al-Dīn, who was with Saladin at the time, noted that "the Sun was eclipsed and it became dark in the daytime. People were frightened and stars appeared." As it happens, ʿImād al-Dīn dates the event one year too early (ah 570); the only large eclipse visible in this region for several years was that of 1176 ce.

Lunar and solar eclipses are fairly frequently visible on Earth's surface 15 days apart, and from time to time such a pair of eclipses may be seen from one and the same location. Such was the case in the summer of 1433 ce, but this occurrence caused some surprise to the contemporary Cairo chronicler al-Maqrīzī:

On Wednesday the 28th of Shawwāl [i.e., June 17], the Sun was eclipsed by about two-thirds in the sign of Cancer more than one hour after the afternoon prayer. The eclipse cleared at sunset. During the eclipse there was darkness and some stars appeared....On Friday night the 14th of Dhū ʾl-Qaʿda [July 3], most of the Moon was eclipsed. It rose eclipsed from the eastern horizon. The eclipse cleared in the time of the nightfall prayer. This is a rarity-the occurrence of a lunar eclipse 15 days after a solar eclipse.

The description of the loss of daylight produced by the solar eclipse is much exaggerated, but otherwise the account is fairly careful.

Medieval Arab astronomers carefully timed the various phases of eclipses by measuring the altitude of the Sun (in the case of a solar eclipse) or of the Moon or a bright star (for a lunar obscuration). These altitude measurements were later converted to local time. For instance, the lunar eclipse of April 22, 981 ce, was recorded by the Cairo astronomer Ibn Yūnus:

This lunar eclipse was in the month of Shawwāl in the year 370 of al-Hijrah [i.e., 370 ah] on the night whose morning was Friday....We gathered to observe this eclipse at Al-Qarāfah [a district of Cairo] in the Mosque of Ibn Nasr al-Maghribī. We perceived the beginning of this eclipse when the altitude of the Moon was approximately 21 deg. About one-quarter of the Moon's diameter was eclipsed. The Moon cleared completely when about ¹/ ₄ of an hour remained to sunrise.

As seen from Cairo, the Moon would reach an altitude of 21° at 3:32 am. The time when the eclipse ended corresponds to 5:09 am.

Certain Arab astronomers used timings of the same lunar eclipse at two separate locations to determine the difference in longitude between the two places. Plans were made for joint observation at the two places based on prediction of the eclipse. For instance, from timings of the lunar eclipse of July 5, 1004 ce, at Ghazna (now Ghaznī, Afghanistan) and Jurjāniyyah (now Kunya-Urgench, Turkm.), the Persian scholar al-Bīrūnī estimated the longitude difference between the two cities as 10.2°. The correct figure is 9.3°. This technique was later widely adopted in Europe.

Uses of eclipses for chronological purposes
Several examples of the value of eclipses in chronology are mentioned above in passing. No one system of dating has been continuously in use since ancient times, although some, such as the Olympiads, persisted for many centuries. Dates were frequently expressed in terms of a king's reign; years were also named after officials of whom lists have been preserved (for instance, the Assyrian Chronicle mentioned above). In such cases, it is important to be able to equate certain specific years thus defined with years before the Christian era (bce). This correspondence can be made whenever the date of an eclipse is given in an ancient record. In this regard, eclipses have distinct advantages over other celestial phenomena such as comets: in addition to being frequently recorded in history, their dates of occurrence can be calculated exactly.

Chinese chronology can be confirmed accurately by eclipses from the 8th century bce (during the Zhou dynasty) onward. The chronicle, mentioned above, notes the occurrence of 36 solar eclipses between 722 and 481 bce-the earliest surviving series of solar eclipse observations from any part of the world. The records give the date of each event in the following form: year of the ruler, lunar month, and day of the 60-day cycle. As many as 32 of the eclipses cited in the Chunqiu can be identified by modern calculations. Errors in the recorded lunar month (typically amounting to no more than a single month) are fairly common, but both the year and the recorded day of the sexagenary cycle are invariably correct.

The chronology of Ptolemy's canon list of kings-which gives the Babylonian series from 747 to 539 bce, the Persian series from 538 to 324 bce, the Alexandrian series from 323 to 30 bce, and the Roman series from 30 bce onward-is confirmed by eclipses. The eclipse of 763 bce, recorded in the Assyrian Chronicle, makes it possible to carry the chronology back with certainty through the period covered by that eponym canon to 910 bce. Identifiable eclipses that were recorded under named Roman consuls extend back to 217 bce. The lunar eclipse seen at Pydna in Macedonia on June 21, 168 bce, and the solar eclipse observed at Rome on March 14, 190 bce, can be used to determine months in the Roman calendar in the natural year. Furthermore, eclipses occasionally help to fix the precise dates of a series of events, such as those associated with the Athenian disaster at Syracuse in 413 bce.

The late Babylonian astronomical texts occasionally mention major historical events, as, for example, the dates when Xerxes and Alexander the Great died. To illustrate the potential of this material for chronological purposes, the date of the death of Xerxes may be accurately fixed by reference to eclipses. On a tablet that lists lunar eclipses at 18-year intervals occurs the following brief announcement between two eclipse records: "Month V, day 14 [?], Xerxes was murdered by his son." Unfortunately, the cuneiform sign for the day of the month is damaged, and a viable reading could be anything from 14 to 18. The year is missing, but it can be deduced from the 18-year sequence as 465 bce. This identification is confirmed by calculating the dates of the two eclipses stated to have occurred in the same year that Xerxes died. The first of these happened when the Moon was in the constellation of Sagittarius, while the second took place on the 14th day of the eighth lunar month. For many years both before and after 465 bce, no such combination of eclipses can be found; it occurs only in 465 bce itself. The dates deduced for the two eclipses are June 5 and November 30 of that year. Mention of an intercalary sixth month on the same tablet enables the date of the death of Xerxes to be fixed as some time between August 4 and 8 in 465 bce.

Uses of eclipses for astronomical purposes
Ancient and medieval observations of eclipses are of the highest value for investigating long-term variations in the length of the day. Early investigators such as the English astronomer Edmond Halley deduced from eclipse observations that the Moon's motion was subject to an acceleration. However, not until 1939 was it conclusively demonstrated (by the British astronomer Harold Spencer Jones) that only part of this acceleration was real. The remainder was apparent and was a consequence of the practice of measuring time relative to a nonuniform unit, namely, the rotation of Earth. Time determined in this way is termed Universal Time. For astronomical purposes, it is preferable to utilize an invariant time frame such as Terrestrial Time (the modern successor to Ephemeris Time)-defined by the motion of the Sun, Moon, and planets.

Lunar and solar tidal friction, occurring especially in the seas and oceans of Earth, is now known to be responsible for a gradual decrease in the terrestrial rate of rotation. Apart from slowing down Earth's rotation, lunar tides produce a reciprocal effect on the Moon's motion, causing a gradual increase in the mean distance of the Moon from Earth (at about 3.8 cm [1.5 inches] per year) and a consequent real retardation of its motion. Hence, the length of the month is slowly increasing (at about 0.04 second in a century). ( See also Moon: Principal characteristics of the Earth-Moon system.)

These changes in the Moon's orbit can now be accurately fixed by lunar laser ranging, and it seems likely that they have proceeded at an essentially constant rate for many centuries. The history of Earth's rotation, however, is complicated by effects of nontidal origin, and in order to obtain maximum information it is necessary to utilize both modern and ancient observations. Telescopic observations reveal fluctuations in the length of the day on timescales of several decades, and these fluctuations are mainly attributed to interactions between the fluid core of Earth and the surrounding solid mantle. Ancient and medieval observations also suggest the presence of longer-term variations, which could be produced by alterations in the moment of inertia of Earth resulting from both the ongoing rise of land that was glaciated during the Pleistocene Ice Age (which ended around 11,700 years ago) and the sea-level changes associated with the freezing and melting of polar ice.

Records of large solar eclipses preserved in literary and historical works have made an important contribution to the study of past variations in Earth's rate of rotation. In recent years, major advances have also come from the analysis of ancient and medieval timings of lunar and solar eclipses by Babylonian and Chinese and Arab astronomers. Although many Babylonian texts are fragmentary, about 120 usable timings of eclipse contacts are accessible (including measurements at different phases of the same eclipse). These observations date primarily from between about 700 and 50 bce. By comparison, only a handful of similar Greek measurements are preserved, and these are less precise. Approximately 80 eclipse timings by Chinese astronomers are preserved in Chinese history. These are from two main periods: between 400 and 600 ce and later from 1000 to 1300. In addition, almost 50 measurements of eclipse times by medieval Arab astronomers are extant; these date from between about 800 and 1000 ce and are mainly contained in the Hakemite Tables compiled by Ibn Yūnus about 1005. Unfortunately, there are very few timings between 50 bce and 400 ce and again from 600 to 800.

Tidal computations indicate a steady increase in the length of the mean solar day by about ¹/ ₄₀ second every millennium. Nontidal causes produce smaller effects, generally in opposition to the main trend. Although the rate of change in the length of the day is minute, the loss of energy by Earth is huge. In measuring changes in Earth's rate of spin, the long timescale covered by ancient observations is an important asset. Approximately one million days, each marginally shorter than at present, have elapsed since the earliest reliable eclipse observations were made, about 700 bce. The contribution of individual small increments is summative. As a result, present-day computations of ancient eclipses that make no allowance for any increase in the length of the day may be as much as five or six hours ahead of the observed time of occurrence. In the case of total solar eclipses, the path of the Moon's shadow across Earth's surface may appear to be displaced by thousands of kilometres.

The technique of using ancient observations to investigate changes in the rate of Earth's rotation is well illustrated by a total solar eclipse observed by Babylonian astronomers on a date corresponding to April 15, 136 bce. This event is recorded on two damaged tablets, a composite translation of which follows:

At 24 degrees after sunrise, there was a solar eclipse beginning on the southwest side. After 18 degrees it became total such that there was complete night. Venus, Mercury, and the normal stars were visible. Jupiter and Mars, which were in their period of disappearance, were visible in that eclipse. [The shadow] moved from southwest to northeast. [Time interval of] 35 degrees for obscuration and clearing up.

This is an exceptionally fine account of a total solar eclipse and is by far the best preserved from the ancient world. The Babylonians were able to detect a number of stars, as well as four planets, during the few minutes of darkness. Modern calculations confirm that Jupiter and Mars were too near the Sun to be observed under normal circumstances; Jupiter was very close to the solar disk.

As noted above, time intervals were expressed by the Babylonians in degrees, each equivalent to 4 minutes of time. Hence, the eclipse is recorded as beginning 96 minutes after sunrise (or about 7:10 am), becoming total 72 minutes later and lasting from start to finish for 140 minutes. Computations that make no allowance for changes in the length of the day displace the track of totality far to the west and imply that this eclipse was barely visible at Babylon, with as little as 15 percent of the Sun being covered. Furthermore, the computed time of onset is around noon rather than in the early morning-a difference of 3.4 hours. In order to best comply with the record, it is necessary to assume that the length of the day has increased by about ¹/ ₃₀ second in the intervening two millennia or so.

Numerous eclipses of both the Sun and the Moon were timed by the Babylonian astronomers with similar care, and analysis of the available records closely confirms the above result for the change in the length of the day. Although the timing device used is likely to have been of low precision, many eclipse observations were made fairly close to the reference moments of sunrise or sunset. For these the measured intervals would be so short that clock errors may be presumed to be small.

The many Arab and Chinese observations of both lunar and solar eclipses during the Middle Ages enable further variations in Earth's spin to be traced. The following observations of the lunar eclipse of September 17, 1019, made by al-Bīrūnī at Ghazna attest to the quality of some of these more recent data:

When I observed it, the altitude of Capella [Alpha Aurigae] above the eastern horizon was slightly less than 60 degrees when the cut at the edge of the Full Moon had become visible; the altitude of Sirius [Alpha Canis Majoris] was [then] 17 degrees, that of Procyon [Alpha Canis Minoris] was 22 degrees and that of Aldebaran [Alpha Tauri] was 63 degrees, where all altitudes are measured from the eastern horizon.

All four stellar measurements are in agreement that the eclipse began at around 2:15 am, but calculations that make no allowance for any change in the length of the day indicate a time approximately 0.5 hour later. Observations such as these reveal that around 1000 ce the length of the day was about ¹/ ₆₅ second shorter than at present.

Combining the various results obtained from analysis of ancient and medieval data, it is possible to show that over the last 2,700 years the rate of increase in the length of the day has varied markedly. This emphasizes the importance of nontidal effects in producing changes in the rate of Earth's rotation period. In sum, the history of Earth's rotation is extremely complex.

F. Richard Stephenson

General

Michael Maunder and Patrick Moore, The Sun in Eclipse (1998), is a guide for observing and photographing eclipses. Pierre Guillermier and Serge Kouchmy, Total Eclipses: Science, Observations, Myths, and Legends (1999), offers a broad cultural view of the phenomenon. J.B. Zirker, Total Eclipses of the Sun, expanded ed. (1995), describes some of the science carried out during past eclipses. Fred Espenak, Fifty Year Canon of Lunar Eclipses, 1986-2035 (1989), provides tables, maps of visibility, and diagrams of the Moon's path through Earth's shadow for every lunar eclipse. W.M. Smart, Textbook on Spherical Astronomy, 6th ed. rev. by R.M. Green (1977), presents the basic tools for calculating occultations and eclipses. Jean Meeus, Elements of Solar Eclipses, 1951-2200 (1989), provides algorithms and tables for computing the circumstances of solar eclipses. Eli Maor, June 8, 2004: Venus in Transit (2000), recounts the history of observation of the transits of Venus beginning in 1639. Leon Golub and Jay Pasachoff, The Solar Corona (1997), discusses coronal physics and recent research, including the contributions of eclipse observations. David Gossman, "Light Curves and Their Secrets," Sky and Telescope, 78(4):410-414 (October 1989), describes the analysis of light curves of eclipsing binaries.

Jack B. Zirker

Historical eclipses

F. Richard Stephenson, Historical Eclipses and Earth's Rotation (1997), discusses in depth ancient and medieval observations of solar and lunar eclipses and their application to studying Earth's past rotation. John M. Steele, Observations and Predictions of Eclipse Times by Early Astronomers (2000), contains a detailed investigation of all known timed eclipse records by pretelescopic astronomers. F. Richard Stephenson, "Computer Dating," Natural History, 96(1):24-29 (January 1987), illustrates how the dates of ancient and medieval events can be refined by using historical eclipses. Works devoted to various aspects of historical astronomy including eclipses are F. Richard Stephenson, "Early Chinese Observations and Modern Astronomy," Sky and Telescope, 97(2):48-55 (February 1999), which has a section on the use of Chinese eclipse records in studying Earth's past rotation; Hermann Hunger and David Pingree, Astral Sciences in Mesopotamia (1999), an overview of recent research into ancient Mesopotamian astronomy that includes a discussion of many Assyrian and Babylonian eclipse records; and Abraham J. Sachs and Hermann Hunger, Astronomical Diaries and Related Texts from Babylonia, vol. 5 of Lunar and Planetary Texts (2001), which contains translations of many texts devoted to eclipse observations and predictions. A pair of authoritative compilations of astronomical data for more than 4,500 years of past and future eclipses are Hermann Mucke and Jean Meeus, Canon of Solar Eclipses −2003 to +2526, 2nd ed. (1992), and Canon of Lunar Eclipses −2002 to +2526, 3rd ed. (1992).

F. Richard Stephenson

# data[].attributes.attachment_link.description
in astronomy, complete or partial obscuring of a celestial body by another. An eclipse occurs when three celestial objects become aligned. From the perspective of a person on...

# data[].attributes.attachment_link.title
Éclipse solaire : comment s’y préparer avec ses élèves

# data[].attributes.attachment_link.description
Pour la première fois depuis 1932, la Lune passera directement devant le Soleil durant l’après-midi du 8 avril 2024, provoquant ainsi une rare éclipse solaire totale dans le ciel de Montréal, de la Montérégie et de l’Estrie. Pendant quelques minutes, le ciel s’assombrira comme en pleine nuit et il sera possible d’admirer la couronne solaire, une partie de l’atmosphère du Soleil habituellement invisible à l’œil nu. Toutefois, ce spectacle céleste comporte son lot de risques, qui peuvent heureusement être amoindris si l’on respecte quelques consignes de sécurité. Voici donc quelques astuces et conseils qui vous permettront de vivre pleinement cette expérience astronomique.

# data[].attributes.attachment_link.description
Grâce à ses services d’accompagnement gratuits et stimulants, Alloprof engage les élèves et leurs parents dans la réussite éducative.

# data[].attributes.attachment_link.provider_name
L\'École branchée - Enseigner à l\'ère du numérique

# data[].attributes.attachment_link.readable_text
Prompt utilisé sur Copilot pour générer l'image de présentation : une image pour illustrer un guide pédagogique axé sur l'observation d'une éclipse solaire à l'école dans un style Pixar, où tous les élèves portent des lunettes de protection. Certains réalisent une activité de codage d'une carte micro:bit à ce sujet, d'autres utilisent une imprimante 3D, d'autres des activités en extérieur pour observer cette éclipse.
👀 Le contexte

Le 8 avril 2024, de nombreux habitants d'Amérique du Nord se préparent à assister à un événement historique : une éclipse solaire totale, un phénomène qui peut se produire seulement une fois dans une vie. La dernière fois que cela s'est produit était en 1972, ce qui en fait un sujet idéal pour engager une conversation intergénérationnelle avec ses parents ou grands-parents. Pour les élèves et les enseignants, c'est également un moment incontournable. Cependant, il est essentiel de prendre des précautions pour observer l'éclipse en toute sécurité.

Avant d'aller plus loin, cliquez sur l'image ci-contre pour observer une représentation interactive à l'échelle du système Soleil-Terre-Lune. Elle permet d'illustrer l'immensité de vide qui sépare ces trois astres et pourquoi l'alignement entre le Soleil la Terre et la Lune lors d'une éclipse de Soleil est un phénomène exceptionnel.

Ce guide propose une série d'activités pour comprendre ce qu'est une éclipse et comment l'observer de manière sécuritaire.

🎯 Intention pédagogique

Les différentes activités proposées permettront aux élèves de :

Expliquer ce qu'est une éclipse solaire totale ainsi que ses causes.

Identifier les conseils et moyens de protection pour observer une éclipse.

Utiliser une carte micro:bit afin de récolter et analyser des informations qui concernent une éclipse.

Imprimer via une imprimante 3D un support de lunettes pour observer une éclipse solaire et une représentation des planètes pour modéliser le déplacement des planètes.

Construire sa boite de protection pour observer l'éclipse solaire.

Réaliser un reportage concernant l'éclipse solaire.

💡 Suggestions d'activités

☝️ Activité 1 : C'est quoi, une éclipse solaire?

Discipline suggérée : Science et technologie
Niveau suggéré : Primaire et secondaire (à adapter selon le niveau)
- Compétence " Chercher des réponses ou des solutions à des problèmes d'ordre scientifique ou technologique ", en invitant les élèves à comprendre le phénomène de l'éclipse solaire, un événement naturel, à travers la recherche et l'observation.
- Terre et espace / Phénomènes astronomiques / Système solaire / Éclipses
Dimensions de la compétence numérique ciblées : 2. Développer et mobiliser ses habiletés technologiques / 3. Exploiter le potentiel du numérique pour l'apprentissage / 4. Développer et mobiliser sa culture informationnelle

L'éclipse solaire aura bientôt lieu! Mais au fait, une éclipse, qu'est-ce que c'est? Comment se produit-elle? Autant de questions qui permettront de mieux cerner le phénomène grâce à la recherche, l'observation et l'utilisation de différents médias. Pour répondre à toutes les interrogations des élèves, les ressources ne manquent pas, et elles n'attendent que vous!

Certains sites proposent beaucoup d'information concernant l'éclipse. Citons par exemple le site eclipsequebec.ca. Une belle première ressource qui permettra à l'élève de récolter de l'information pour expliquer ce phénomène et mieux le comprendre.

Ensuite, différentes vidéos ciblant les enfants pourront vous permettre d'expliquer le mécanisme d'une éclipse avec une bonne vulgarisation :
Envie de valider les connaissances de vos élèves à ce stade?
Voici un petit questionnaire interactif créé à l'aide de BookWidgets qui permet de réviser les éléments importants à retenir quant à l'éclipse au Québec plus précisément. Faites balayer ce code QR aux élèves pour qu'ils puissent y accéder de leur appareil.

Vous avez envie de créer votre propre activité sur BookWidgets? On vous en dit plus dans la section " Tutoriels " à la fin, pour obtenir toutes les ressources!

L'analyse de modèles interactifs

Pour des élèves un rien plus grands (3e cycle du primaire - 5-6 e année et 1er cycle du secondaire - 7 e à 9 e année), il existe différentes modélisations 3D qui pourront vous permettre d'aborder les différents mouvements qui provoquent les éclipses.

Ce premier exemple est gratuit et facilement accessible : le site Simulations interactives PhET (colorado.edu) qui contient différentes modélisations, dont certaines pouvant se rattacher à l'analyse d'une éclipse. Ainsi, en utilisant par exemple la simulation suivante, on pourra aisément comprendre que la Lune tourne autour de la Terre, que la Terre tourne autour du Soleil. L'utilisation de cette simulation se fera en parallèle avec une grille d'observation et des consignes d'écriture que l'enseignant rédigera par rapport à ses objectifs.

Enfin, et si vous disposez de tablettes dans votre école, l'utilisation de la réalité augmentée pourrait également être une alternative intéressante et motivante. Ainsi, c'est via l'application Foxar que des simulations similaires à la précédente pourront être utilisées directement par les élèves. L'application est gratuite et, en se créant un compte anonyme, une majorité d'expériences seront ainsi disponibles.

☝️ Activité 2 : Éclipse solaire : les bons gestes de sécurité

Afin de pouvoir observer l'éclipse en toute sécurité, les élèves devront comprendre quel est le matériel approprié pour cette activité, mais également comment l'utiliser de manière optimale.

Pour cela, notons que le site eclipsequebec.ca propose directement les conseils fondamentaux ainsi que le matériel nécessaire. Toutefois, voici une autre idée d'activité permettant aux élèves d'identifier ce qu'il convient de faire pour observer en toute sécurité!

Utilisez aussi cette animation interactive gratuite d'eduMedia pour montrer aux élèves ce qu'il se passera concrètement et l'effet des lunettes de protection.

Comme les éclipses solaires ne sont pas un nouveau phénomène, il est raisonnable de supposer que d'autres personnes ont déjà pensé à des moyens sûrs et efficaces pour les observer. Dans cette perspective, on vous propose d'utiliser des vidéos immersives à 360 degrés pour montrer aux élèves les méthodes de protection et comment les utiliser en toute sécurité lors de l'observation d'une éclipse. Voici quelques suggestions qu'on trouve sur YouTube :
360°, Solar eclipse on Tidore Island, 8K video (youtube.com) 360º Total Solar Eclipse Experience 4K - Indonesia 2016 - YouTube Experience the Solar Eclipse in 360 | Daily 360 | The New York Times (youtube.com) Total Solar Eclipse: 360 VR Video Seen From Space | Earth From Space | BBC Earth (youtube.com)
Voici aussi une suggestion de déroulement pour vivre cette activité :

1 : Objectif : Utiliser la réalité virtuelle pour simuler une éclipse solaire, permettant aux élèves d'explorer les mouvements célestes et les conditions nécessaires pour qu'une éclipse se produise.

2 : Matériel nécessaire : Appareils compatibles avec la réalité virtuelle (casques VR avec YouTube VR, tablettes, ou simplement un téléphone avec YouTube).
3 : Déroulement de l'activité :

Introduction : Commencez par une présentation sur les éclipses solaires, expliquant les types d'éclipses, les phases, et l'alignement du soleil, de la Terre, et de la lune.

Découverte de la réalité virtuelle : Introduisez les élèves à la technologie de réalité virtuelle. Expliquez comment elle peut être utilisée pour simuler des environnements et des phénomènes qui ne sont pas facilement accessibles dans le monde réel.

Exploration virtuelle : Utilisez l'application ou le logiciel choisi pour guider les élèves à travers une simulation d'éclipse solaire. Encouragez-les à observer les moyens de protection utilisé, la manière de les utiliser. Si les moyens de protection sont inexistants sur certaines des personnes, faites réagir vos élèves!

Discussion et réflexion : Après l'expérience virtuelle, organisez une discussion sur ce qu'ils ont observé. Posez des questions pour approfondir leur compréhension des éclipses solaires et de l'importance des moyens de protection. Mettez en perspective les observations avec les informations récoltées dans l'activité précédente.

NB : au préalable, n'hésitez pas à réaliser certaines captures d'écran de ces vidéos en 360°. Cela vous permettra, par exemple, de faire réagir les élèves sur des morceaux choisis, et de faciliter la synthèse des observations. Cette activité peut également permettre d'expliquer l'éclipse solaire totale en elle-même, et non pas que les moyens de protection utilisables.

4 : Prolongement de l'activité : Pour conclure de manière amusante, voici une activité d'observation qui demande de classer les images selon que tous les personnages observent correctement l'éclipse ou non! Vos élèves ont-ils le sens de l'observation?

L'exercice a été créé à l'aide du site Learningapps.

☝️ Activité 3 : Je fabrique mon matériel pour observer l'éclipse!

Les différentes activités précédentes nous auront permis de comprendre qu'une bonne protection pour observer une éclipse est indispensable. Afin de pouvoir mieux équiper les élèves, il n'est pas toujours nécessaire d'acheter et de dépenser sans compter. Ainsi, la meilleure activité pédagogique consistera certainement à fabriquer son propre matériel de protection. Une très bonne occasion de développer des compétences à la fois numériques, mais également collaboratives et qui touche à la préhension fine des élèves. Une pointe de créativité leur permettra également d'apporter une touche personnelle à ce matériel de protection. C'est parti pour travailler avec son âme de " maker "!

Plusieurs tutoriels et sites expliquent comment construire sa propre boîte d'observation d'une éclipse solaire. Le premier site que nous vous conseillons de consulter : Comment fabriquer une boîte à éclipse solaire | Agence spatiale canadienne (asc-csa.gc.ca) Il détaille comment fabriquer avec trois fois rien son matériel d'observation. À la portée de tous, grands ou petits!

Source : Comment fabriquer une boîte à éclipse solaire | Agence spatiale canadienne (asc-csa.gc.ca)

Et si cela ne suffit pas, pourquoi ne pas utiliser une vidéo de style " tutoriel " avec vos élèves? En voici un exemple réalisé par Les Débrouillards, qui est bien adaptée aux jeunes du primaire.

NB : Si vous maîtrisez quelques bases en montage vidéo, et que vous possédez le matériel adapté, la réalisation de votre propre vidéo pourrait bien être également une activité pédagogique en soi!

✌️ Pour faire un pas de plus : Programmer une carte micro:bit pour étudier le phénomène

L'objectif de cette nouvelle activité sera de faire comprendre aux élèves le mécanisme des éclipses solaires à travers la programmation d'un micro:bit simulant le mouvement de la Lune devant le Soleil. De la même manière que nous l'avons déjà traité dans le guide SCOOP! concernant les tempêtes de neige, il s'agit ici de pouvoir réaliser une activité en lien avec les STIAM (sciences, technologies, ingénierie, arts et mathématiques), tout en profitant d'un événement important de l'actualité.

Vous ne savez ni utiliser une carte micro:bit ni le logiciel de codage qui est prévu avec? Direction la section " Tutoriels " à la fin de ce guide pour en apprendre plus!

1 : Objectif de l'activité : Faire comprendre aux élèves le mécanisme des éclipses solaires à travers la programmation d'une carte micro:bit pour simuler le mouvement de la Lune devant le Soleil.

Cartes de codage micro:bit

Ordinateurs ou tablettes avec accès à un éditeur de code micro:bit (par exemple, MakeCode)

Matériaux pour créer des maquettes simplifiées du Soleil, de la Terre, et de la Lune (optionnel)

Prompt utilisé sur Copilot : Une image dans un style de film Pixar, où deux élèves (un garçon et une fille) codent une carte micro :bit pour étudier les éclipses solaires

Introduction : Commencez par une discussion sur les éclipses solaires, en expliquant le rôle du Soleil, de la Terre, et de la Lune. Utilisez des illustrations ou des animations pour montrer comment l'alignement de ces trois corps célestes crée une éclipse solaire.

Exploration des cartes de codage micro:bit : Introduisez les élèves à la carte micro:bit et à son éditeur de code. Expliquez les bases de la programmation en utilisant l'interface de l'éditeur MakeCode ou un environnement similaire.

Activité de codage : Le défi pour les élèves : programmer le micro:bit pour qu'il simule une éclipse solaire. Ils peuvent utiliser les lumières DEL intégrées pour représenter le Soleil et la Lune. Par exemple, un grand cercle de DEL allumées peut représenter le Soleil, et un petit cercle de LED éteintes se déplaçant à travers le grand cercle peut simuler la Lune passant devant le Soleil.

Les élèves peuvent travailler en petits groupes pour concevoir leur code, encourager la collaboration et le partage des idées.

Présentation et discussion : À la fin du temps imparti,chaque groupe présente sa simulation d'éclipse solaire. Discutez de la précision de la simulation et de ce que chaque groupe a appris sur les éclipses solaires à travers cette activité.

Extension (optionnel) : Si le temps et les ressources le permettent, les élèves peuvent construire une maquette physique du système Soleil-Terre-Lune et intégrer leur micro:bit programmée pour simuler dynamiquement une éclipse solaire.

2 : Matériel nécessaire :
Cette activité aide non seulement à comprendre le phénomène des éclipses solaires d'une manière interactive et engageante, mais renforce également l'utilisation du numérique comme outil d'apprentissage et de création, en lien avec les objectifs de développement de la compétence numérique.

✌️ Pour faire un pas de plus : Reproduire une éclipse solaire en 3D
3 : Déroulement de l'activité :
Pour réaliser une activité combinant l'usage d'une imprimante 3D et l'étude des éclipses solaires, vous pouvez envisager un projet où les élèves conçoivent et impriment en 3D des modèles du système Soleil-Terre-Lune. Cette activité permettrait non seulement de comprendre le phénomène des éclipses solaires, mais aussi de développer la compétence numérique en lien avec la production de contenu et l'innovation technologique.

Voici une proposition de déroulement.

1. Objectif : Créer des modèles 3D qui démontrent comment les éclipses solaires se produisent, en se basant sur la position relative du Soleil, de la Terre, et de la Lune.
Prompt utilisé sur Copilot : une image dans un style de film Pixar, où deux élèves (un garçon et une fille), utilisent une imprimante 3D pour représenter le mouvement d'une éclipse solaire

Ordinateurs avec logiciel de conception 3D (comme Tinkercad ou SketchUp)

Imprimante 3D

Filaments pour imprimante 3D

Introduction : Commencez par expliquer les concepts clés des éclipses solaires, y compris les positions et mouvements du Soleil, de la Terre, et de la Lune.

Recherche et conception : Les élèves recherchent les dimensions relatives et les distances entre le Soleil, la Terre, et la Lune. Ils utilisent ces informations pour concevoir leurs modèles 3D. Ils reçoivent ensuite une introduction aux bases de la modélisation 3D en utilisant un logiciel de conception adapté.

Modélisation 3D : Les élèves créent des modèles du système Soleil-Terre-Lune en utilisant le logiciel de conception 3D. Ils doivent réfléchir à la meilleure façon de représenter une éclipse solaire.

Impression 3D : Après la finalisation des modèles, procédez à l'impression 3D. Discutez des choix de conception et des ajustements nécessaires pour réussir l'impression.

Présentation et discussion : Les élèves présentent leurs modèles imprimés et expliquent comment ceux-ci illustrent le phénomène de l'éclipse solaire. Discussion sur les défis rencontrés pendant la modélisation et l'impression.

Extension (optionnel) : Proposez aux élèves de créer un petit documentaire vidéo expliquant le processus de conception et d'impression, ainsi que les principes scientifiques derrière les éclipses solaires.

Afin de réaliser différents projets à l'aide d'une imprimante 3D, nous vous recommandons d'utiliser le logiciel en ligne Tinkercad. Simple d'utilisation et à la portée des élèves dès le primaire, il sera une solution accessible et gratuite (même sans pour autant réaliser un projet avec une imprimante 3D).
2. Matériel :
Vous n'avez jamais utilisé Tinkecad? On vous propose un tout ce qu'il faut pour le prendre en mains dans la section Tutoriels à la fin de ce guide!
3 Déroulement de l'activité :
🚀 D'autres idées à explorer

Générer des images à l'aide de l'IA

Dans l'une des activités précédentes, on a utilisé des images pour identifier des moyens de protection et les bonnes pratiques liées à l'observation d'une éclipse solaire. La génération d'images par IA a été d'un grand appui pour obtenir une variété d'images. On vous explique ici comment on peut procéder.

À noter : en ce moment, le ministère de l'Éducation du Québec recommande de réserver la génération de contenus par IA aux enseignants seulement. Ils sont les seuls à " avoir les mains sur le clavier " pour réaliser ces différents exemples. Pour aller plus loin, on vous recommande les tâches en lien avec la génération d'images par IA proposées par le Service national du RÉCIT, domaine de l'Univers social : RÉCIT univers social(recitus.qc.ca)

Étape 1 : Demander à une IA telle que Copilot de Microsoft de créer une image à partir d'une requête (prompt).

En restant évasif dans la requête, on note que les images n'échappent pas aux stéréotypes et ne rendent pas toujours parfaitement la demande. Dans ce cas, on pourrait faire appel aux élèves pour identifier ce qui doit être précisé dans la requête.

Par conséquent, en modifiant adéquatement les requêtes, il devrait être possible d'obtenir un résultat illustrant les personnages observant l'éclipse de la manière la plus appropriée. Cette activité offre ainsi une double opportunité : éduquer sur l'utilisation des intelligences artificielles génératives d'images tout en explorant le thème des éclipses solaires!

Prolongement de l'activité : afin de pouvoir obtenir une image de qualité, où l'on montre correctement les mesures de protection, une autre possibilité est de s'adjoindre les options du Studio magique de l'application Canva.

Ainsi, on peut ajuster l'image en ajoutant / effaçant / modifiant les parties qui posent un problème de sécurité pour une observation optimale de l'éclipse.

Comment faire? Importez tout d'abord l'image générée par l'IA précédemment. Sélectionnez ensuite l'outil approprié (dans ce cas précis, nous utiliserons l'édition magique).

Sélectionnez avec votre curseur la zone de l'image à modifier. Celle-ci nous permettra dans l'étape suivante d'ajouter les lunettes de protection pour pouvoir observer l'éclipse.

Discutez et échangez avec vos élèves afin d'évaluer les lunettes qui pourront être les plus adaptées pour observer ce phénomène. Placez-les ensuite sur la tête des personnages de l'image.

Enfin, parmi les autres possibilités : effacer tout simplement les personnages ne portant pas de protection.

Fabriquer un robot conversationnel

Et si au lieu de donner directement toutes les informations aux élèves, l'enseignante ou l'enseignant utilisait un robot conversationnel, ou chabot, avec ses élèves? Ce n'est plus de la science-fiction!

Voici comment concevoir un robot conversationnel qui agira comme un expert en éclipse devant accompagner l'élève dans ses questionnements.

Afin de réaliser cette petite prouesse aussi simplement et rapidement que possible, nous vous recommandons le site https://huggingface.co/chat/. Cette IA générative a la particularité d'être libre et gratuite, et ne nécessite pas la création de compte.

Pour créer votre nouvel assistant personnel, à partir du tableau de bord, rendez-vous dans l'onglet " Assistants ". Optez ensuite pour la création d'un nouvel assistant en haut à droite.

Voici une capture d'écran qui illustre le tout.

Configurez ensuite les différentes informations qui vous permettront d'atteindre votre objectif avec les élèves.

Pour cet exercice, voici la demande qui correspond à sa configuration. Vous pouvez copier directement ou ajuster selon vos besoins. Collez le tout dans la case " Instructions ", à droite.

Crée un assistant virtuel qui sert de guide expert pour l'observation des éclipses solaires. Cet assistant doit combiner des connaissances en astronomie avec des compétences pédagogiques (pour les élèves du primaire au secondaire) pour offrir une expérience d'apprentissage engageante et informative.

L'assistant devra d'abord comprendre à qui il s'adresse (un enseignant, ou un élève?). Il demande ensuite l'âge et le niveau scolaire pour adapter sa réponse.

1) Fournir des conseils de sécurité :

Expliquer pourquoi il est dangereux de regarder directement le soleil sans protection adéquate.

Détaillez les types de lunettes de sécurité spéciales pour éclipse, y compris comment les choisir et les utiliser correctement.

Offrir des alternatives sûres pour observer une éclipse sans lunettes spéciales, comme les méthodes de projection.

Offrir des informations pédagogiques sur les éclipses :

2) Expliquer les types d'éclipses solaires (totale, partielle, annulaire) et ce qui les cause.

Fournir des faits intéressants sur les éclipses solaires, leur histoire, et leur signification dans différentes cultures.

Proposer des activités pédagogiques et des expériences pour les élèves, comme la création de modèles du système solaire ou l'utilisation de la technologie (par exemple, des applications de réalité augmentée) pour simuler une éclipse.

Intégration de la technologie éducative :

3) Recommander des applications, des logiciels, ou des ressources en ligne qui peuvent enrichir l'expérience d'observation des éclipses solaires.

Guider les utilisateurs à travers des tutoriels ou des simulations interactives sur les éclipses.

Personnalisation des expériences d'apprentissage :

4) Adapter les conseils et les informations en fonction de différents niveaux d'âge et de compréhension.

Encourager les questions et offrir des réponses personnalisées pour approfondir la compréhension des élèves.

Mettre à jour les informations sur les prochaines éclipses :
DÉBUT DE LA COMMANDE :
5) Fournir des détails sur les dates, les heures, et les meilleurs lieux d'observation pour les prochaines éclipses solaires visibles dans différentes régions.

Cet assistant virtuel devrait être conçu pour être accessible, facile à utiliser, et attrayant pour un large public, y compris les élèves, les enseignants, et les amateurs d'astronomie. Il devrait être capable de susciter la curiosité, d'encourager l'apprentissage actif, et de promouvoir une observation sûre des éclipses solaires.

Envie de tester directement ce robot conversationnel? C'est par ici! : https://hf.co/chat/assistant/65d781fa339ebcf1e0fd132a

🔎Des tutoriels à utiliser

🔎 Pour en savoir plus

Formation Premier pas avec micro:bit (développement professionnel, Campus RÉCIT)

Dessin en 3D avec Thinkercad (développement professionnel, Campus RÉCIT)

Éclipse Totale de Soleil (eclipsequebec.ca)
FIN DE LA COMMANDE!
Prépare-toi à une éclipse solaire totale! | Parlons sciences
Créer un exercice sur Learningapps
Éclipse totale de Soleil du 8 avril 2024 (youtube.com)
Collection de ressources gratuites par eduMedia Éclipses solaires visibles de Québec (Canada) (tutiempo.net) Se préparer à l'éclipse solaire totale du 8 avril 2024 au Québec | Gouvernement du Québec (quebec.ca) Au cœur de l'éclipse du 8 avril 2024 | La Presse Une rare éclipse solaire totale sera visible à Montréal le 8 avril 2024 | Radio-Canada Où et quand regarder l'éclipse solaire du 8 avril? Comment le faire en sécurité? | Radio-Canada Prochaines éclipses visibles du Canada | Agence spatiale canadienne (asc-csa.gc.ca) La Lune chez les Autochtones | Agence spatiale canadienne (asc-csa.gc.ca) Une lune parmi tant d'autres (pour les éducateurs) | Agence spatiale canadienne (asc-csa.gc.ca) La Lune, un monde à part (pour les éducateurs) | Agence spatiale canadienne (asc-csa.gc.ca) Trousse pour les éducateurs et les jeunes sur les éclipses lunaires et solaires | Agence spatiale canadienne (asc-csa.gc.ca)

# data[].attributes.attachment_link.title
L'éclipse dont tout le monde parle! - École branchée

# data[].attributes.attachment_link.description
Le 8 avril 2024, de nombreux habitants d'Amérique du Nord se préparent à assister à un événement historique : une éclipse solaire totale, un phénomène qui peut se produire seulement une fois dans une vie. Voici une foule d'idées d'activités autour de ce thème!

# data[].attributes.headline
Resources for Parents: (Created by LEARN)

# data[].attributes.subject
Resources for Parents: (Created by LEARN)

# data[].attributes.attachment_link.title
Solar Eclipse events _ évènements liés à l'éclipse.pdf

# data[].attributes.attachment_link.readable_text
Curio is your go-to site for CBC/Radio-Canada content carefully selected for its relevance to every subject area. Learning comes alive with Curio. / Curio est votre ressource pour trouver des contenus de CBC/Radio-Canada sélectionnés avec soin pour leur pertinence dans l'enseignement de chaque matière. Avec Curio, les apprentissages prennent vie.

# data[].attributes.attachment_link.description
Une éclipse solaire totale s’en vient le 8 avril dans l’est du Canada. Cette Minute MAJ avec Mathilde Boucher t’explique tout ce que tu as besoin de savoir!

# data[].attributes.attachment_link.readable_text
Écris à la manière du Curieux!
A- Avant l'éclipse
Après avoir lu la fiche du écris un article informatif sur le sujet.

Ton objectif: expliquer à des élèves d'un pays, d'où l'éclipse ne sera pas visible, ce qui se passera le 8 avril.

leur donner les informations permettant de savoir ce qui va se dérouler
👉 Pour t'aider : ton texte doit répondre aux questions: qui, quoi, quand, où.

puis leur expliquer dans tes mots le phénomène de l'éclipse.
👉 Relis la fiche sur l'éclipse pour t'aider.
👉 Tu peux aussi regarder ces vidéos:

⚠️ Comme les journalistes, dans ce texte, tu ne dois pas donner ton avis ni écrire au " je ".
Pour aller plus loin
Enregistre ton commentaire d'explication de l'éclipse sur cette vidéo d'ÉduMedia .
B- Après l'éclipse
✔️Écris un article pour expliquer maintenant ce qui s'est réellement passé le 8 avril.👉 Décris ce qui était visible, combien de temps cela a duré, quelle a été la réaction des personnes autour de toi, etc.

⚠️ Comme les journalistes, dans ce texte, tu ne dois pas donner ton avis ni écrire au " je ".

✔️ Ajoute un petit texte personnel dans lequel tu expliques comment cette journée s'est passée pour toi : raconte ce que tu as vu, ce que tu as ressenti (nomme tes émotions: peur, émerveillement, surprise, déception, etc.)
👉Pour ce texte, tu peux écrire au " je " comme tu le ferais dans un texte pour un journal intime ou dans une lettre envoyée à un.e ami.e.

# data[].attributes.attachment_link.description
Une éclipse solaire totale aura lieu le 8 avril prochain. Le Curieux a créé deux fiches explicatives et vous propose des activités!