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Earth Facts

Check out our range of fun planet Earth facts for kids and find interesting information about our world, including facts related to volcanoes, earthquakes, minerals, structures, gas and much more.

Children will love the cool trivia, did you know facts and other interesting Earth info that will help them learn a thing or two along the way. Read on and enjoy learning about the amazing planet we live on.

Magma is the hot liquid rock under the surface of the Earth, it is known as lava after it comes out of a volcano.

Natural gas doesn't have an odour, strong smells are added to it by humans so it can be detected when there are leaks.

Hawaii is moving towards Japan at the speed of 10cm a year. This is because they are on different tectonic plates.

The world's largest desert (outside of the polar regions) is the Sahara, it covers about one third of Africa!

Stretching out to an impressive length of 6696 kilometres (4160 miles) long, the Nile River is the longest river on earth.

The volcanic rock known as pumice is the only rock that can float in water.

Mt Everest is the highest mountain on earth, its peak reaches 8,848 metres (29029 feet) above sea level. Check out the highest mountains on each continent of the Earth.

On average the Atlantic Ocean is the saltiest of Earth's major oceans.

Scientists have the dated the Earth as being between 4 and 5 billion years old!

Talc is the softest mineral found on Earth, reaching just 1 on Mohs scale of hardness, it is often used to make talcum powder.

The Niagara Falls are located on the border of the USA and Canada.

Rock found at the bottom of the Grand Canyon is around 2 billion years old.

Although earthquakes can be deadly, most are very small and not even felt by humans.

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Planet Earth Facts for Kids - Interesting Information about Our World

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Earth Facts Check out our range of fun planet Earth facts for kids and find interesting information about our world, including facts related to volcanoes, earthquakes, minerals, structures, gas and much more. Children will love the cool trivia, did you know facts and other interesting Earth info that will help them learn a thing or two along the way.

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The Atacama Desert in northern Chile is the driest place on Earth. It is said that a city there went without rain for 400 years! And yet, this desert is right next to the biggest body of water on Earth, the Pacific Ocean. Do you know what they say about the ocean? Water, water everywhere, but not a drop to drink.

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DID YOU KNOW?

* Thanks to Earth's "axial tilt," which exposes more or less of our planet's northern and southern hemispheres to the sun depending on the time of year (and is also responsible for our seasons), some spots near the poles experience 24 hours of straight daylight or darkness.

* Earth's rotation combined with its core of molten nickel and iron generates a magnetic field, shielding us from solar radiation while creating light shows-called auroras-that are literally out of this world.

* Earth's land masses move, a phenomenon known as "continental drift." They creep about as fast as your fingernails grow.

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Space: Mission to Earth -- National Geographic Kids

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DID YOU KNOW? * Thanks to Earth's "axial tilt," which exposes more or less of our planet's northern and southern hemispheres to the sun depending on the time of year (and is also responsible for our seasons), some spots near the poles experience 24 hours of straight daylight or darkness.

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Kids learn about the planet Earth of the Solar System including fun facts, mass, day, year, and distance from the Sun. Astronomy for kids and teachers.

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You better pack for a long trip when you trek to Neptune, the most distant of our solar system's planets. It's so far away, in fact, that it's the only planet you can't see from Earth with the naked eye. How did astronomers discover a planet they couldn't even see? Through math! They noticed that Uranus -Neptune's nearest planetary neighbor-traveled in a way that suggested the gravitational pull of an eighth planet. Crunching the numbers revealed Neptune, first confirmed through a telescope in 1846.

You won't need sunglasses for this voyage. High noon on Neptune is no brighter than the last few moments of sunset on Earth. Not that you could stand on Neptune at noon. Like Jupiter and Saturn, Neptune is a gas giant-a big ball of gas surrounding an Earth-size core of hot liquids rather than rocks or other solid matter. And like fellow "ice giant" Uranus, Neptune's atmosphere is composed mostly of water, ammonia, and methane. It's the methane that gives Neptune its striking blue hue. You'll want to keep your ship soaring high in the planet's atmosphere, which extends down to crushing depths and is home to the windiest weather in the solar system. Clouds of frozen methane whoosh as fast as a fighter jet through storms the size of Earth. Please wear your seatbelt for the duration of your flight above Neptune.

MORE FACTS

* A day on Neptune is 16 hours, but a year lasts 165 Earth years. Barely one Neptune year has passed since the planet's discovery in 1846.

* Neptune has six rings and 13 confirmed moons. One of these moons, Triton, has geysers that spray icy material more than five miles (eight kilometers) high into the frigid atmosphere.

* Neptune's magnetic field is 27 times mightier than Earth's.

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Mission to Neptune - Get facts about this planet

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You better pack for a long trip when you trek to Neptune, the most distant of our solar system's planets. It's so far away, in fact, that it's the only planet you can't see from Earth with the naked eye. How did astronomers discover a planet they couldn't even see?

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Kids learn about the ice giant planet Neptune of the Solar System including fun facts, mass, day, year, and distance from the Sun. Astronomy for kids and teachers.

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Quick facts for kidsNeptune

Discovery

Discovered by
Urbain Le Verrier
John Couch Adams
Johann Galle

Discovery date

September 23, 1846

Designations

Adjectives

Neptunian

Orbital characteristics

Epoch J2000

Aphelion

4,553,946,490 km
30.44125206 AU

Perihelion

4,452,940,833 km
29.76607095 AU

4,503,443,661 km
30.10366151 AU

Eccentricity

0.011214269

60,190 days
164.79 years
89,666 Neptune solar days

Inclination

1.767975° to Ecliptic
6.43° to Sun's equator
0.72° to Invariable plane

Known satellites
13

Physical characteristics

24,622±19 km

Flattening

0.0171 ± 0.0013

7.6408×10 ⁹ km²
14.98 Earths

Volume

6.254×10 ¹³ km³
57.74 Earths

Mass

1.0243×10 ²⁶ kg
17.147 Earths

11.15 m/s²
1.14g

0.6713 day
16 h 6 min 36 s

Equatorial rotation velocity

2.68 km/s
9,660 km/h

19 h 57 m 20 s

Albedo

0.290 ( bond)
0.41 ( geom.)

Surface temp.

min

mean

max

1 bar level

72 K

0.1 bar (10 kPa)

55 K

2.2″-2.4″

Atmosphere

Composition by volume

Neptune, is the eighth and last planet from the Sun in the Solar System. It is a gas giant. It is the fourth largest planet and third heaviest. Neptune has four rings which are hard to see from the Earth. It is 17 times heavier than Earth and is a little bit heavier than Uranus. It was named after the Roman God of the Sea.

Neptune's atmosphere is mostly made up of hydrogen and helium. It also contains small amounts of methane which makes the planet appear blue. Neptune's blue color is much brighter compared to Uranus', which has a similar amount of methane, so there might be another reason why Neptune is blue. Neptune also has the strongest winds of any planet in the solar system, measured as high as 2,100 km/h or 1,300 mph.

Neptune was discovered by the astronomers, Urbain Le Verrier and John Couch Adams. They were both honored for the discovery. The planet was the first to be discovered by mathematical calculations instead of using a telescope. Because of Uranus' odd movements in its orbit (the line which a planet follows in moving), it made astronomers search for the new planet. The planet was visited by only one spacecraft, on August 25, 1989. Neptune once had a huge storm known as the "Great Dark Spot" which was discovered in 1989 by Voyager 2. However, the dark spot was not seen in 1994, and new spots were found since then. It is not known why the dark spot disappeared. Visits by more space probes have been proposed.

In 1821, Alexis Bouvard published the astronomical tables of the orbit of Uranus. Later observations showed that Uranus was moving in an irregular way in its orbit, making some astronomers think of another large body being the cause of the irregular motions of Uranus. In 1843, John Couch Adams calculated the orbit of an eighth planet that would possibly be influencing the orbit of Uranus. He sent his calculations to Sir George Airy, the Astronomer Royal, who asked Adams for an explanation. Adams began to make a copy of the reply, but never sent it.

In 1846, Urbain Le Verrier, who was not working with Adams, made his own calculations but also failed to get much attention from French astronomers. However, in the same year, John Herschel began to support the mathematical method and encouraged James Challis to search for the planet. After much delay, Challis began his unwilling search in July 1846. Meanwhile, Le Verrier had convinced Johann Gottfried Galle to search for the planet.

After the news of the discovery of Neptune spread, there was also a lot of arguing between the French and the British about who was to be deserved credit for the discovery. Later, an international agreement decided that both Le Verrier and Adams together deserved credit. However, historians are now reviewing the topic after the rediscovery in 1998 of the "Neptune papers" (historical documents from the Royal Greenwich Observatory), which had seemingly been stolen by astronomer Olin Eggen for nearly three decades and were only rediscovered (in his ownership) right after his death. After reviewing the documents, some historians now think that Adams does not deserve equal credit with Le Verrier.

Shortly after its discovery, Neptune was temporarily called "the planet exterior to Uranus" or "Le Verrier's planet". The first suggestion for a name came from Galle. He proposed the name . In England, Challis suggested the name . In France, Arago suggested that the new planet be called Leverrier, a suggestion which was met with a lot of opposition outside France. French almanacs promptly reintroduced the name Herschel for Uranus and Leverrier for the new planet.

Meanwhile, on separate and different reason, Adams suggested changing the name Georgian to Uranus, while Leverrier (through the Board of Longitude) suggested Neptune for the new planet. Struve gave support of that name on December 29, 1846, to the Saint Petersburg Academy of Sciences. Soon Neptune was internationally agreed among many people and was then the official name for the new planet. In Roman mythology, Neptune was the god of the sea, identified with the Greek god, Poseidon.

Mass and composition

At 10.243×10 ²⁵ kg, Neptune's mass puts the planet between Earth and the largest gas giants; Neptune has seventeen Earth masses but just 1/18th the mass of Jupiter. Neptune and Uranus are often considered to be part of a sub-class of gas giant known as " ice giants", given their smaller size and big differences in composition compared to Jupiter and Saturn. In the search for extrasolar planets, Neptune has been used as a reference to determine the size and structure of the discovered planet. Some discovered planets that have similar masses like Neptune are often called "Neptunes". just as astronomers refer to various extra-solar "Jupiters."

The atmosphere of Neptune is made up mostly of hydrogen, with a smaller amount of helium. A tiny amount of methane is also detected in the atmosphere. Important absorption bands of methane happen at wavelengths above 600 nm, in the red and infrared portion of the spectrum. This absorption of red light by the atmospheric methane gives Neptune its blue hue.

Because Neptune orbits so far from the Sun, it gets very little heat with the uppermost regions of the atmosphere at −218 °C (55 K). Deeper inside the layers of gas, however, the temperature rises slowly. Like Uranus, the source of this heating is unknown, but the differences are larger: Neptune is the farthest planet from the Sun, yet its internal energy is strong enough to create the fastest winds seen in the Solar System. Several possible explanations have been suggested, including radiogenic heating from the planet's core, the continued radiation into space of leftover heat made by infalling matter during the planet's birth, and gravity waves breaking above the tropopause.

Weather and magnetic field

In 1989, the Great Dark Spot, a cyclonic storm system the size of Eurasia, was discovered by NASA's spacecraft. The storm resembled the Great Red Spot of Jupiter. However, on November 2, 1994, the Hubble Space Telescope did not see the Great Dark Spot on the planet. Instead, a new storm similar to the Great Dark Spot was found in the planet's northern hemisphere. The reason why the Great Dark Spot has disappeared is unknown. One possible theory is that heat transfer from the planet's core disrupted the atmospheric balance and existing circulation patterns. The Scooter is another storm, a white cloud group farther south than the Great Dark Spot. Its nickname was given when it was first noticed in the months leading up to the Voyager encounter in 1989: it moved faster than the Great Dark Spot. Later images showed clouds that moved even faster than Scooter. The Wizard's eye/ Dark Spot 2 is another southern cyclonic storm, the second most strongest storm seen during the 1989 encounter. It originally was completely dark, but as Voyager came closer to the planet, a bright core developed and is seen in most of the highest resolution images.

Unlike other gas giants, Neptune's atmosphere shows the presence of high clouds making shadows on a thick cloud deck below. Though Neptune's atmosphere is much more active than that of Uranus, both planets are made up of the same gases and ices. Uranus and Neptune are not exactly the same type of gas giants like to Jupiter and Saturn, but are rather ice giants, meaning they have a larger solid core and are also made of ices. Neptune is very cold, with temperatures as low as −224 °C (−372 °F or 49 K) recorded at the cloud tops in 1989.

Neptune's Rings

Very small blue colored rings have been discovered around the blue planet, but they are not as well known as the rings of Saturn. When these rings were discovered by a team led by Edward Guinan, originally they thought that the rings may not be complete rings. However, this was proven wrong by Voyager 2. Neptune's planetary rings have a weird "clumpy" arrangement. Although the cause is currently unknown but some scientists think that it may be because of the gravitational contact with small moons that orbit near them.

Proof that the rings are incomplete first began in the mid-1980s, when stellar occultation were found to rarely show an extra "blink" just before or after the planet occulted the star. Pictures from Voyager 2 in 1989 solved the problem, when the ring system was found to have several faint rings. The farthest ring, Adams, has three famous arcs now named Liberté, Egalité, and Fraternité (Liberty, Equality, and Fraternity).

The existence of arcs is very hard to understand because the laws of motion would predict that arcs spread out into a single ring in a very short time. The gravitational effects of Galatea, a moon just inward from the ring, are now thought to have created the arcs.

Several other rings were discovered by the Voyager cameras. Also with the thin Adams Ring about 63,000 km from the center of Neptune, the Leverrier Ring is at 53,000 km and the wider, smaller Galle Ring is at 42,000 km. A very small outward expansion to the Leverrier Ring has been named Lassell; it is surrounded at its outer edge by the Arago Ring at 57,000 km.

New Earth-based observations published in 2005 appeared to show that Neptune's rings are a lot more unstable than thought before. To be exact, it looks like that the Liberté ring might disappear maybe quickly in less than 100 years. The new observations seems to puzzle our understanding of Neptune's rings into a lot of confusion.

Neptune has 14 known moons. Triton is the largest Neptunian moon, comprising more than 99.5% of the mass in orbit around Neptune, and it is the only one massive enough to be spheroidal. Triton was discovered by William Lassell just 17 days after the discovery of Neptune itself. Unlike all other large planetary moons in the Solar System, Triton has a retrograde orbit, indicating that it was captured rather than forming in place; it was probably once a dwarf planet in the Kuiper belt. It is close enough to Neptune to be locked into a synchronous rotation, and it is slowly spiralling inward because of tidal acceleration. It will eventually be torn apart, in about 3.6 billion years, when it reaches the Roche limit. In 1989, Triton was the coldest object that had yet been measured in the Solar System, with estimated temperatures of 38 K (−235 °C).

From July to September 1989, Voyager 2 discovered six moons of Neptune. Of these, the irregularly shaped Proteus is notable for being as large as a body of its density can be without being pulled into a spherical shape by its own gravity. Although the second-most-massive Neptunian moon, it is only 0.25% the mass of Triton. Neptune's innermost four moons- Naiad, Thalassa, Despina and Galatea-orbit close enough to be within Neptune's rings. The next-farthest out, Larissa, was originally discovered in 1981 when it had occulted a star. This occultation had been attributed to ring arcs, but when Voyager 2 observed Neptune in 1989, Larissa was found to have caused it. Five new irregular moons discovered between 2002 and 2003 were announced in 2004. A new moon and the smallest yet, Neptune XIV, was found in 2013. Because Neptune was the Roman god of the sea, Neptune's moons have been named after lesser sea gods.
Neptune's largest moon - Triton
Observation

Neptune cannot be seen with naked eye alone, since Neptune's normal brightness are between magnitudes +7.7 and +8.0, which can be out-shined by Jupiter's Galilean moons, the dwarf planet Ceres, and the asteroids 4 Vesta, 2 Pallas, 7 Iris, 3 Juno and 6 Hebe. A telescope or strong binoculars will show Neptune as a small blue dot, similar in appearance to Uranus. The blue color comes from the methane in its atmosphere. Its small obvious size has made it difficult to study visually; most telescopic data was quite limited until the arrival of the Hubble Space Telescope and large ground-based telescopes with adaptive optics.

Exploration

is the only spacecraft that has visited Neptune. The spacecraft's closest approach to the planet occurred on 25 August 1989. Because this was the last major planet the spacecraft could visit, it was decided to make a close flyby of the moon Triton, regardless of the consequences to the trajectory, similarly to what was done for 's encounter with Saturn and its moon Titan. The images relayed back to Earth from Voyager 2 became the basis of a 1989 PBS all-night program, Neptune All Night.

During the encounter, signals from the spacecraft required 246 minutes to reach Earth. Hence, for the most part, Voyager 2's mission relied on preloaded commands for the Neptune encounter. The spacecraft performed a near-encounter with the moon Nereid before it came within 4,400 km of Neptune's atmosphere on 25 August, then passed close to the planet's largest moon Triton later the same day.

The spacecraft verified the existence of a magnetic field surrounding the planet and discovered that the field was offset from the centre and tilted in a manner similar to the field around Uranus. Neptune's rotation period was determined using measurements of radio emissions and Voyager 2 also showed that Neptune had a surprisingly active weather system. Six new moons were discovered, and the planet was shown to have more than one ring.

The flyby also provided the first accurate measurement of Neptune's mass which was found to be 0.5 percent less than previously calculated. The new figure disproved the hypothesis that an undiscovered Planet X acted upon the orbits of Neptune and Uranus.

After the Voyager 2 flyby mission, the next step in scientific exploration of the Neptunian system, is considered to be a Flagship orbital mission. Such a hypothetical mission is envisioned to be possible in the late 2020s or early 2030s. However, there have been discussions to launch Neptune missions sooner. In 2003, there was a proposal in NASA's "Vision Missions Studies" for a "Neptune Orbiter with Probes" mission that does Cassini-level science. Another, more recent proposal was for Argo, a flyby spacecraft to be launched in 2019, that would visit Jupiter, Saturn, Neptune, and a Kuiper belt object. The focus would be on Neptune and its largest moon Triton to be investigated around 2029. The proposed New Horizons 2 mission (which was later scrapped) might also have done a close flyby of the Neptunian system.

Images for kids

Four images taken a few hours apart with the NASA/ESA Hubble Space Telescope's Wide Field Camera 3. Near infrared radiation data has been used as red channel.

In 2018, the European Southern Observatory developed unique laser-based methods to get clear and high-resolution images of Neptune from the surface of Earth.

The Great Dark Spot in a color-uncalibrated image by Voyager 2.

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Quick facts for kidsNeptune Discovery Discovered by Urbain Le Verrier John Couch Adams Johann Galle Discovery date September 23, 1846 Designations Adjectives Neptunian Orbital characteristics Epoch J2000 Aphelion 4,553,946,490 km 30.44125206 AU Perihelion 4,452,940,833 km 29.76607095 AU 4,503,443,661 km 30.10366151 AU Eccentricity 0.011214269 60,190 days 164.79 years 89,666 Neptune solar

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Kids learn about the ice giant planet Uranus of the Solar System including fun facts, mass, day, year, and distance from the Sun. Astronomy for kids and teachers.

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Kids learn about the ice giant planet Uranus of the Solar System including fun facts, mass, day, year, and distance from the Sun. Astronomy for kids and teachers.

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Discovery

Discovered by
William Herschel

Discovery date

13 March 1781

Designations

Pronunciation

or

the Latin form Ūranus of the Greek god Οὐρανός Ouranos

Adjectives

Uranian

Orbital characteristics

Epoch J2000

Aphelion

20.0965 AU (3006.39 Gm)

Perihelion

18.2861 AU (2735.56 Gm)

19.19126 AU (2870.972 Gm)

Eccentricity

0.04717

142.238600°

Inclination

74.006°

96.998857°

Known satellites
27

Physical characteristics

25,362±7 km

25,559±4 km
4.007 Earths

24,973±20 km
3.929 Earths

Flattening

0.0229±0.0008

Circumference

159,354.1 km

8.1156×10 ⁹ km ²
15.91 Earths

Volume

6.833×10 ¹³ km ³
63.086 Earths

Mass

(8.6810±0.0013)×105,793,939±13 km ²⁵ kg
14.536 Earths
GM= ³/s ²

1.27 g/cm ³

8.69 m/s²
0.886 g

0.23 (estimate)

−0.71832 d
−17 h 14 m 23 s
(retrograde)

−0.71833 d
−17 h 14 min 24 s
(retrograde)

Equatorial rotation velocity

2.59 km/s
9,320 km/h

17 h 9 m 15 s
257.311°

Albedo

0.300 ( Bond)
0.488 ( geom.)

Surface temp.

min

mean

max

1 bar level

76 K
(−197.2 °C)

0.1 bar
(tropopause)

47 K

53 K

57 K

−7.2

3.3″ to 4.1″

Atmosphere

Composition by volume

Below 1.3 bar (130 kPa): Icy volatiles:

Uranus is the seventh planet from the Sun and is a gaseous cyan ice giant. Most of the planet is made of water, ammonia, and methane in a supercritical phase of matter, which in astronomy is called 'ice' or volatiles. The planet's atmosphere has a complex layered cloud structure and has the lowest minimum temperature of 49 K (−224 °C; −371 °F) out of all Solar System's planets. It has a marked axial tilt of 97.8° with a retrograde rotation rate of 17 hours. This means that in an 84 Earth years orbital period around the Sun, its poles get around 42 years of continuous sunlight, followed by 42 years of continuous darkness.

Uranus has the third-largest diameter and fourth-largest mass among the Solar System's planets. Based on current models, inside its volatile mantle layer is a rocky core, and surrounding it is a thick hydrogen and helium atmosphere. Trace amounts of hydrocarbons (thought to be produced via hydrolysis) and carbon monoxide along with carbon dioxide (thought to have been originated from comets) have been detected in the upper atmosphere. There are many unexplained climate phenomena in Uranus's atmosphere, such as its peak wind speed of 900 km/h (560 mph), variations in its polar cap and its erratic cloud formation. The planet also has very low internal heat compared to other giant planets, which is still unexplained.

Like the other giant planets, Uranus has a ring system, orbiting natural satellites and a magnetosphere. Its ring system is extremely dark, with only about 2% of the incoming light reflected, and contains the known 13 inner moons. Further out are the larger five major moons of the planet: Miranda, Ariel, Umbriel, Titania, and Oberon; and orbiting at much greater distance from Uranus are the known nine irregular moons. The planet's magnetosphere is highly asymmetric and has many charged particles, which may cause the darkening of its rings and moons.

Uranus is visible to the naked eye, but it is very dim and was not classified as a planet until 1781, when it was first observed by William Herschel. About seven decades after its discovery, consensus was reached that the planet be named from the Greek god Uranus (Ouranos), one of the Greek primordial deities. As of 2023, it was visited up close only once when in 1986 the probe flew by the planet. Though nowadays it can be resolved and observed by telescopes, there is much desire to revisit the planet, as shown by Planetary Science Decadal Survey's decision to make the proposed Uranus Orbiter and Probe mission a top priority in the 2023-2032 survey.

Like the classical planets, Uranus is visible to the naked eye, but it was never recognised as a planet by ancient observers because of its dimness and slow orbit. Sir William Herschel first observed Uranus on 13 March 1781, leading to its discovery as a planet, expanding the known boundaries of the Solar System for the first time in history and making Uranus the first planet classified as such with the aid of a telescope.

Uranus had been observed on many occasions before its recognition as a planet, but it was generally mistaken for a star. Possibly the earliest known observation was by Hipparchos, who in 128 BC might have recorded it as a star for his star catalogue that was later incorporated into Ptolemy's . The earliest definite sighting was in 1690, when John Flamsteed observed it at least six times, cataloguing it as 34 Tauri. The French astronomer Pierre Charles Le Monnier observed Uranus at least twelve times between 1750 and 1769, including on four consecutive nights.

Herschel recorded in his journal: "In the quartile near ζ Tauri ... either [a] Nebulous star or perhaps a comet." On 17 March he noted: "I looked for the Comet or Nebulous Star and found that it is a Comet, for it has changed its place." When he presented his discovery to the Royal Society, he continued to assert that he had found a comet, but also implicitly compared it to a planet:

The power I had on when I first saw the comet was 227. From experience I know that the diameters of the fixed stars are not proportionally magnified with higher powers, as planets are; therefore I now put the powers at 460 and 932, and found that the diameter of the comet increased in proportion to the power, as it ought to be, on the supposition of its not being a fixed star, while the diameters of the stars to which I compared it were not increased in the same ratio. Moreover, the comet being magnified much beyond what its light would admit of, appeared hazy and ill-defined with these great powers, while the stars preserved that lustre and distinctness which from many thousand observations I knew they would retain. The sequel has shown that my surmises were well-founded, this proving to be the Comet we have lately observed.

Herschel notified the Astronomer Royal Nevil Maskelyne of his discovery and received this flummoxed reply from him on 23 April 1781: "I don't know what to call it. It is as likely to be a regular planet moving in an orbit nearly circular to the sun as a Comet moving in a very eccentric ellipsis. I have not yet seen any coma or tail to it."

Although Herschel continued to describe his new object as a comet, other astronomers had already begun to suspect otherwise. Finnish-Swedish astronomer Anders Johan Lexell, working in Russia, was the first to compute the orbit of the new object. Its nearly circular orbit led him to the conclusion that it was a planet rather than a comet. Berlin astronomer Johann Elert Bode described Herschel's discovery as "a moving star that can be deemed a hitherto unknown planet-like object circulating beyond the orbit of Saturn". Bode concluded that its near-circular orbit was more like a planet's than a comet's.

The object was soon universally accepted as a new planet. By 1783, Herschel acknowledged this to Royal Society president Joseph Banks: "By the observation of the most eminent Astronomers in Europe it appears that the new star, which I had the honour of pointing out to them in March 1781, is a Primary Planet of our Solar System." In recognition of his achievement, King George III gave Herschel an annual stipend of £200 (equivalent to £19,000 in 2021) on condition that he moved to Windsor so that the Royal Family could look through his telescopes.

The name Uranus references the ancient Greek deity of the sky Uranus ( Ancient Greek: ), known as Caelus in Roman mythology, the father of Cronus ( Saturn) and grandfather of Zeus ( Jupiter), which was rendered as Uranus in Latin. It is the only one of the eight planets whose English name derives from a figure of Greek mythology. The adjectival form of Uranus is "Uranian". The pronunciation of the name Uranus preferred among astronomers is , with stress on the first syllable as in Latin Uranus, in contrast to , with stress on the second syllable and a long a, though both are considered acceptable.

Consensus on the name was not reached until almost 70 years after the planet's discovery. During the original discussions following discovery, Maskelyne asked Herschel to "do the astronomical world the faver [] to give a name to your planet, which is entirely your own, [and] which we are so much obliged to you for the discovery of". In response to Maskelyne's request, Herschel decided to name the object Georgium Sidus (George's Star), or the "Georgian Planet" in honour of his new patron, King George III. He explained this decision in a letter to Joseph Banks:

In the fabulous ages of ancient times the appellations of Mercury, Venus, Mars, Jupiter and Saturn were given to the Planets, as being the names of their principal heroes and divinities. In the present more philosophical era it would hardly be allowable to have recourse to the same method and call it Juno, Pallas, Apollo or Minerva, for a name to our new heavenly body. The first consideration of any particular event, or remarkable incident, seems to be its chronology: if in any future age it should be asked, when this last-found Planet was discovered? It would be a very satisfactory answer to say, 'In the reign of King George the Third'.

Herschel's proposed name was not popular outside Britain and Hanover, and alternatives were soon proposed. Astronomer Jérôme Lalande proposed that it be named Herschel in honour of its discoverer. Swedish astronomer Erik Prosperin proposed the names Astraea, Cybele (now the names of asteroids), and , which would become the name of the next planet to be discovered. The name was supported by other astronomers who liked the idea to commemorate the victories of the British Royal Naval fleet in the course of the American Revolutionary War by calling the new planet even Neptune George III or Neptune Great Britain, a compromise Lexell suggested as well. Daniel Bernoulli, suggested Hypercronius and Transaturnis. Georg Lichtenberg from Göttingen suggested Austräa, a goddess mentioned by Ovid (but who is traditionally associated with Virgo). The name was also proposed.

In a March 1782 treatise, Bode proposed Uranus, the Latinised version of the Greek god of the sky, Ouranos. Bode argued that the name should follow the mythology so as not to stand out as different from the other planets, and that Uranus was an appropriate name as the father of the first generation of the Titans. He also noted that elegance of the name in that just as Saturn was the father of Jupiter, the new planet should be named after the father of Saturn. Bode was however apparently unaware that Uranus was only the Latinised form of the titular deity, and his Roman equivalent was Caelus. In 1789, Bode's Royal Academy colleague Martin Klaproth named his newly discovered element uranium in support of Bode's choice. Ultimately, Bode's suggestion became the most widely used, and became universal in 1850 when HM Nautical Almanac Office, the final holdout, switched from using Georgium Sidus to Uranus.

Uranus has two astronomical symbols. The first to be proposed, , was proposed by Johann Gottfried Köhler at Bode's request in 1782. Köhler suggested that the new planet be given the symbol for platinum, which had been described scientifically only 30 years before. As there was no alchemical symbol for platinum, he suggested ⛢ or ⛢, a combination of the planetary-metal symbols ☉ (gold) and ♂ (iron), as platinum (or 'white gold') is found mixed with iron. Bode thought that an upright orientation, ⛢, fit better with the symbols for the other planets while remaining distinct. This symbol predominates in modern astronomical use in the rare cases that symbols are used at all. The second symbol, , was suggested by Lalande in 1784. In a letter to Herschel, Lalande described it as "un globe surmonté par la première lettre de votre nom" ("a globe surmounted by the first letter of your surname"). The second symbol is nearly universal in astrology.

Uranus is called by a variety of names in other languages. Uranus's name is literally translated as the "sky king star" in Chinese (天王星), Japanese (天王星), Korean (천왕성), and Vietnamese ( sao Thiên Vương). In Thai, its official name is Dao Yurenat (ดาวยูเรนัส), as in English. Its other name in Thai is Dao Maruettayu (ดาวมฤตยู, Star of Mṛtyu), after the Sanskrit word for 'death', Mrtyu (मृत्यु). In Mongolian, its name is Tengeriin Van (Тэнгэрийн ван), translated as 'King of the Sky', reflecting its namesake god's role as the ruler of the heavens. In Hawaiian, its name is Heleʻekala, the Hawaiian rendering of the name 'Herschel'. In Māori, its name is Whērangi.

It is argued that the differences between the ice giants and the gas giants arise from their formation history. The Solar System is hypothesised to have formed from a rotating disk of gas and dust known as the presolar nebula. Much of the nebula's gas, primarily hydrogen and helium, formed the Sun, and the dust grains collected together to form the first protoplanets. As the planets grew, some of them eventually accreted enough matter for their gravity to hold on to the nebula's leftover gas. The more gas they held onto, the larger they became; the larger they became, the more gas they held onto until a critical point was reached, and their size began to increase exponentially. The ice giants, with only a few Earth masses of nebular gas, never reached that critical point. Recent simulations of planetary migration have suggested that both ice giants formed closer to the Sun than their present positions, and moved outwards after formation (the Nice model).

Orbit and rotation

The rotational period of the interior of Uranus is 17 hours, 14 minutes. As on all giant planets, its upper atmosphere experiences strong winds in the direction of rotation. At some latitudes, such as about 60 degrees south, visible features of the atmosphere move much faster, making a full rotation in as little as 14 hours.

The Uranian axis of rotation is approximately parallel to the plane of the Solar System, with an axial tilt of 97.77° (as defined by prograde rotation). This gives it seasonal changes completely unlike those of the other planets. (Pluto and the protoplanet-asteroid 2 Pallas also have extreme axial tilts.) Near the solstice, one pole faces the Sun continuously and the other faces away, with only a narrow strip around the equator experiencing a rapid day-night cycle, with the Sun low over the horizon. On the other side of Uranus's orbit, the orientation of the poles towards the Sun is reversed. Each pole gets around 42 years of continuous sunlight, followed by 42 years of darkness. Near the time of the equinoxes, the Sun faces the equator of Uranus, giving a period of day-night cycles similar to those seen on most of the other planets.

One result of this axis orientation is that, averaged over the Uranian year, the near-polar regions of Uranus receive a greater energy input from the Sun than its equatorial regions. Nevertheless, Uranus is hotter at its equator than at its poles. The underlying mechanism that causes this is unknown. The reason for Uranus's unusual axial tilt is also not known with certainty, but the usual speculation is that during the formation of the Solar System, an Earth-sized protoplanet collided with Uranus, causing the skewed orientation. Research by Jacob Kegerreis of Durham University suggests that the tilt resulted from a rock larger than Earth crashing into the planet 3 to 4 billion years ago. Uranus's south pole was pointed almost directly at the Sun at the time of Voyager 2's flyby in 1986. The labelling of this pole as "south" uses the definition currently endorsed by the International Astronomical Union, namely that the north pole of a planet or satellite is the pole that points above the invariable plane of the Solar System, regardless of the direction the planet is spinning. A different convention is sometimes used, in which a body's north and south poles are defined according to the right-hand rule in relation to the direction of rotation.

Visibility from Earth

Internal structure

Uranus's mass is roughly 14.5 times that of Earth, making it the least massive of the giant planets. Its diameter is slightly larger than Neptune's at roughly four times that of Earth. A resulting density of 1.27 g/cm ³ makes Uranus the second least dense planet, after Saturn. This value indicates that it is made primarily of various ices, such as water, ammonia, and methane. The total mass of ice in Uranus's interior is not precisely known, because different figures emerge depending on the model chosen; it must be between 9.3 and 13.5 Earth masses. Hydrogen and helium constitute only a small part of the total, with between 0.5 and 1.5 Earth masses. The remainder of the non-ice mass (0.5 to 3.7 Earth masses) is accounted for by rocky material. The standard model of Uranus's structure is that it consists of three layers: a rocky ( silicate/iron-nickel) core in the centre, an icy mantle in the middle and an outer gaseous hydrogen/helium envelope. The core is relatively small, with a mass of only 0.55 Earth masses and a radius less than 20% of Uranus'; the mantle comprises its bulk, with around 13.4 Earth masses, and the upper atmosphere is relatively insubstantial, weighing about 0.5 Earth masses and extending for the last 20% of Uranus's radius. Uranus's core density is around 9 g/cm ³, with a pressure in the centre of 8 million bars (800 GPa) and a temperature of about 5000 K. The ice mantle is not in fact composed of ice in the conventional sense, but of a hot and dense fluid consisting of water, ammonia and other volatiles. This fluid, which has a high electrical conductivity, is sometimes called a water-ammonia ocean.

The extreme pressure and temperature deep within Uranus may break up the methane molecules, with the carbon atoms condensing into crystals of diamond that rain down through the mantle like hailstones. This phenomenon is similar to diamond rains that are theorised by scientists to exist on Jupiter, Saturn, and Neptune. Very-high-pressure experiments at the Lawrence Livermore National Laboratory suggest that the base of the mantle may comprise an ocean of metallic liquid carbon, perhaps with floating solid 'diamond-bergs'.

The bulk compositions of Uranus and Neptune are different from those of Jupiter and Saturn, with ice dominating over gases, hence justifying their separate classification as ice giants. There may be a layer of ionic water where the water molecules break down into a soup of hydrogen and oxygen ions, and deeper down superionic water in which the oxygen crystallises but the hydrogen ions move freely within the oxygen lattice.

Although the model considered above is reasonably standard, it is not unique; other models also satisfy observations. For instance, if substantial amounts of hydrogen and rocky material are mixed in the ice mantle, the total mass of ices in the interior will be lower, and, correspondingly, the total mass of rocks and hydrogen will be higher. Presently available data does not allow a scientific determination of which model is correct. The fluid interior structure of Uranus means that it has no solid surface. The gaseous atmosphere gradually transitions into the internal liquid layers. For the sake of convenience, a revolving oblate spheroid set at the point at which atmospheric pressure equals 1 bar (100 kPa) is conditionally designated as a "surface". It has equatorial and polar radii of 25,559 ± 4 km (15,881.6 ± 2.5 mi) and 24,973 ± 20 km (15,518 ± 12 mi), respectively. This surface is used throughout this article as a zero point for altitudes.

Internal heat

Uranus's internal heat appears markedly lower than that of the other giant planets; in astronomical terms, it has a low thermal flux. Why Uranus's internal temperature is so low is still not understood. Neptune, which is Uranus's near twin in size and composition, radiates 2.61 times as much energy into space as it receives from the Sun, but Uranus radiates hardly any excess heat at all. The total power radiated by Uranus in the far infrared (i.e. heat) part of the spectrum is times the solar energy absorbed in its atmosphere. Uranus's heat flux is only , which is lower than the internal heat flux of Earth of about . The lowest temperature recorded in Uranus's tropopause is 49 K (−224.2 °C; −371.5 °F), making Uranus the coldest planet in the Solar System.

One of the hypotheses for this discrepancy suggests that when Uranus was hit by a supermassive impactor, which caused it to expel most of its primordial heat, it was left with a depleted core temperature. This impact hypothesis is also used in some attempts to explain the planet's axial tilt. Another hypothesis is that some form of barrier exists in Uranus's upper layers that prevents the core's heat from reaching the surface. For example, convection may take place in a set of compositionally different layers, which may inhibit upward heat transport; perhaps double diffusive convection is a limiting factor.

In a 2021 study, the ice giants' interior conditions were mimicked by compressing water containing minerals like olivine and ferropericlase, thus showing that large amounts of magnesium could be dissolved in the liquid interiors of Uranus and Neptune. If Uranus has more of this magnesium than Neptune, it could form a thermal insulation layer, thus potentially explaining the planet's low temperature.

Atmosphere

Although there is no well-defined solid surface within Uranus's interior, the outermost part of Uranus's gaseous envelope that is accessible to remote sensing is called its 0.1 and 10 atmosphere. Remote-sensing capability extends down to roughly 300 km below the 1 bar (100 kPa) level, with a corresponding pressure around 100 bar (10 MPa) and temperature of 320 K (47 °C; 116 °F). The tenuous thermosphere extends over two planetary radii from the nominal surface, which is defined to lie at a pressure of 1 bar. The Uranian atmosphere can be divided into three layers: the troposphere, between altitudes of −300 and 50 km (−186 and 31 mi) and pressures from 100 to 0.1 bar (10 MPa to 10 kPa); the stratosphere, spanning altitudes between 50 and 4,000 km (31 and 2,485 mi) and pressures of between −10 bar (10 kPa to 10 µPa); and the thermosphere extending from 4,000 km to as high as 50,000 km from the surface. There is no mesosphere.

Composition

The composition of Uranus's atmosphere is different from its bulk, consisting mainly of molecular hydrogen and helium. The helium molar fraction, i.e. the number of helium atoms per molecule of gas, is in the upper troposphere, which corresponds to a mass fraction . This value is close to the protosolar helium mass fraction of , indicating that helium has not settled in its centre as it has in the gas giants. The third-most-abundant component of Uranus's atmosphere is methane (CH). Methane has prominent absorption bands in the visible and near-infrared (IR), making Uranus aquamarine or cyan in colour. Methane molecules account for 2.3% of the atmosphere by molar fraction below the methane cloud deck at the pressure level of 1.3 bar (130 kPa); this represents about 20 to 30 times the carbon abundance found in the Sun.

The mixing ratio is much lower in the upper atmosphere due to its extremely low temperature, which lowers the saturation level and causes excess methane to freeze out. The abundances of less volatile compounds such as ammonia, water, and hydrogen sulfide in the deep atmosphere are poorly known. They are probably also higher than solar values. Along with methane, trace amounts of various hydrocarbons are found in the stratosphere of Uranus, which are thought to be produced from methane by photolysis induced by the solar ultraviolet (UV) radiation. They include ethane (CH), acetylene (CH), methylacetylene (CHCH), and diacetylene (CHCH). Spectroscopy has also uncovered traces of water vapour, carbon monoxide and carbon dioxide in the upper atmosphere, which can only originate from an external source such as infalling dust and comets.

Troposphere

The troposphere is the lowest and densest part of the atmosphere and is characterised by a decrease in temperature with altitude. The temperature falls from about 320 K (47 °C; 116 °F) at the base of the nominal troposphere at −300 km to 53 K (−220 °C; −364 °F) at 50 km. The temperatures in the coldest upper region of the troposphere (the tropopause) actually vary in the range between 49 and 57 K (−224 and −216 °C; −371 and −357 °F) depending on planetary latitude. The tropopause region is responsible for the vast majority of Uranus's thermal far infrared emissions, thus determining its effective temperature of 59.1 ± 0.3 K (−214.1 ± 0.3 °C; −353.3 ± 0.5 °F).

The troposphere is thought to have a highly complex cloud structure; water clouds are hypothesised to lie in the pressure range of 50 to 100 bar (5 to 10 MPa), ammonium hydrosulfide clouds in the range of 20 to 40 bar (2 to 4 MPa), ammonia or hydrogen sulfide clouds at between 3 and 10 bar (0.3 and 1 MPa) and finally directly detected thin methane clouds at 1 to 2 bar (0.1 to 0.2 MPa). The troposphere is a dynamic part of the atmosphere, exhibiting strong winds, bright clouds and seasonal changes.

Upper atmosphere

The middle layer of the Uranian atmosphere is the stratosphere, where temperature generally increases with altitude from 53 K (−220 °C; −364 °F) in the tropopause to between 800 and 850 K (527 and 577 °C; 980 and 1,070 °F) at the base of the thermosphere. The heating of the stratosphere is caused by absorption of solar UV and IR radiation by methane and other hydrocarbons, which form in this part of the atmosphere as a result of methane photolysis. Heat is also conducted from the hot thermosphere. The hydrocarbons occupy a relatively narrow layer at altitudes of between 100 and 300 km corresponding to a pressure range of 1000 to 10 Pa and temperatures of between 75 and 170 K (−198 and −103 °C; −325 and −154 °F).

The most abundant hydrocarbons are methane, acetylene and ethane with mixing ratios of around 10 −7 relative to hydrogen. The mixing ratio of carbon monoxide is similar at these altitudes. Heavier hydrocarbons and carbon dioxide have mixing ratios three orders of magnitude lower. The abundance ratio of water is around 7×10 −9. Ethane and acetylene tend to condense in the colder lower part of the stratosphere and tropopause (below 10 mBar level) forming haze layers, which may be partly responsible for the bland appearance of Uranus. The concentration of hydrocarbons in the Uranian stratosphere above the haze is significantly lower than in the stratospheres of the other giant planets.

The outermost layer of the Uranian atmosphere is the thermosphere and corona, which has a uniform temperature around 800 K (527 °C) to 850 K (577 °C). The heat sources necessary to sustain such a high level are not understood, as neither the solar UV nor the auroral activity can provide the necessary energy to maintain these temperatures. The weak cooling efficiency due to the lack of hydrocarbons in the stratosphere above 0.1 mBar pressure levels may contribute too. In addition to molecular hydrogen, the thermosphere-corona contains many free hydrogen atoms. Their small mass and high temperatures explain why the corona extends as far as 50,000 km (31,000 mi), or two Uranian radii, from its surface.

This extended corona is a unique feature of Uranus. Its effects include a drag on small particles orbiting Uranus, causing a general depletion of dust in the Uranian rings. The Uranian thermosphere, together with the upper part of the stratosphere, corresponds to the ionosphere of Uranus. Observations show that the ionosphere occupies altitudes from 2,000 to 10,000 km (1,200 to 6,200 mi). The Uranian ionosphere is denser than that of either Saturn or Neptune, which may arise from the low concentration of hydrocarbons in the stratosphere. The ionosphere is mainly sustained by solar UV radiation and its density depends on the solar activity. Auroral activity is insignificant as compared to Jupiter and Saturn.

Main page: Climate of Uranus

At ultraviolet and visible wavelengths, Uranus's atmosphere is bland in comparison to the other giant planets, even to Neptune, which it otherwise closely resembles. When Voyager 2 flew by Uranus in 1986, it observed a total of 10 cloud features across the entire planet. One proposed explanation for this dearth of features is that Uranus's internal heat is markedly lower than that of the other giant planets, as stated previously Uranus is the coldest planet in the Solar System.

Banded structure, winds and clouds

In 1986, Voyager 2 found that the visible southern hemisphere of Uranus can be subdivided into two regions: a bright polar cap and dark equatorial bands. Their boundary is located at about −45° of latitude. A narrow band straddling the latitudinal range from −45 to −50° is the brightest large feature on its visible surface. It is called a southern "collar". The cap and collar are thought to be a dense region of methane clouds located within the pressure range of 1.3 to 2 bar (see above). Besides the large-scale banded structure, Voyager 2 observed ten small bright clouds, most lying several degrees to the north from the collar. In all other respects, Uranus looked like a dynamically dead planet in 1986.

Voyager 2 arrived during the height of Uranus's southern summer and could not observe the northern hemisphere. At the beginning of the 21st century, when the northern polar region came into view, the Hubble Space Telescope (HST) and Keck telescope initially observed neither a collar nor a polar cap in the northern hemisphere. So Uranus appeared to be asymmetric: bright near the south pole and uniformly dark in the region north of the southern collar. In 2007, when Uranus passed its equinox, the southern collar almost disappeared, and a faint northern collar emerged near 45° of latitude. In 2023, a team employing the Very Large Array observed a dark collar at 80° latitude, and a bright spot at the north pole, indicating the presence of a polar vortex.

In the 1990s, the number of the observed bright cloud features grew considerably, partly because new high-resolution imaging techniques became available. Most were found in the northern hemisphere as it started to become visible. An early explanation-that bright clouds are easier to identify in its dark part, whereas in the southern hemisphere the bright collar masks them - was shown to be incorrect. Nevertheless, there are differences between the clouds of each hemisphere. The northern clouds are smaller, sharper and brighter. They appear to lie at a higher altitude. The lifetime of clouds spans several orders of magnitude. Some small clouds live for hours; at least one southern cloud may have persisted since the Voyager 2 flyby. Recent observation also discovered that cloud features on Uranus have a lot in common with those on Neptune. For example, the dark spots common on Neptune had never been observed on Uranus before 2006, when the first such feature dubbed Uranus Dark Spot was imaged. The speculation is that Uranus is becoming more Neptune-like during its equinoctial season.

The tracking of numerous cloud features allowed determination of zonal winds blowing in the upper troposphere of Uranus. At the equator winds are retrograde, which means that they blow in the reverse direction to the planetary rotation. Their speeds are from −360 to −180 km/h (−220 to −110 mph). Wind speeds increase with the distance from the equator, reaching zero values near ±20° latitude, where the troposphere's temperature minimum is located. Closer to the poles, the winds shift to a prograde direction, flowing with Uranus's rotation. Wind speeds continue to increase reaching maxima at ±60° latitude before falling to zero at the poles. Wind speeds at −40° latitude range from 540 to 720 km/h (340 to 450 mph). Because the collar obscures all clouds below that parallel, speeds between it and the southern pole are impossible to measure. In contrast, in the northern hemisphere maximum speeds as high as 860 km/h (540 mph) are observed near +50° latitude.

Seasonal variation

For a short period from March to May 2004, large clouds appeared in the Uranian atmosphere, giving it a Neptune-like appearance. Observations included record-breaking wind speeds of 820 km/h (510 mph) and a persistent thunderstorm referred to as "Fourth of July fireworks". On 23 August 2006, researchers at the Space Science Institute (Boulder, Colorado) and the University of Wisconsin observed a dark spot on Uranus's surface, giving scientists more insight into Uranus atmospheric activity. Why this sudden upsurge in activity occurred is not fully known, but it appears that Uranus's extreme axial tilt results in extreme seasonal variations in its weather. Determining the nature of this seasonal variation is difficult because good data on Uranus's atmosphere has existed for less than 84 years, or one full Uranian year. Photometry over the course of half a Uranian year (beginning in the 1950s) has shown regular variation in the brightness in two spectral bands, with maxima occurring at the solstices and minima occurring at the equinoxes. A similar periodic variation, with maxima at the solstices, has been noted in microwave measurements of the deep troposphere begun in the 1960s. Stratospheric temperature measurements beginning in the 1970s also showed maximum values near the 1986 solstice. The majority of this variability is thought to occur owing to changes in viewing geometry.

There are some indications that physical seasonal changes are happening in Uranus. Although Uranus is known to have a bright south polar region, the north pole is fairly dim, which is incompatible with the model of the seasonal change outlined above. During its previous northern solstice in 1944, Uranus displayed elevated levels of brightness, which suggests that the north pole was not always so dim. This information implies that the visible pole brightens some time before the solstice and darkens after the equinox. Detailed analysis of the visible and microwave data revealed that the periodical changes in brightness are not completely symmetrical around the solstices, which also indicates a change in the meridional albedo patterns.

In the 1990s, as Uranus moved away from its solstice, Hubble and ground-based telescopes revealed that the south polar cap darkened noticeably (except the southern collar, which remained bright), whereas the northern hemisphere demonstrated increasing activity, such as cloud formations and stronger winds, bolstering expectations that it should brighten soon. This indeed happened in 2007 when it passed an equinox: a faint northern polar collar arose, and the southern collar became nearly invisible, although the zonal wind profile remained slightly asymmetric, with northern winds being somewhat slower than southern.

The mechanism of these physical changes is still not clear. Near the summer and winter solstices, Uranus's hemispheres lie alternately either in full glare of the Sun's rays or facing deep space. The brightening of the sunlit hemisphere is thought to result from the local thickening of the methane clouds and haze layers located in the troposphere. The bright collar at −45° latitude is also connected with methane clouds. Other changes in the southern polar region can be explained by changes in the lower cloud layers. The variation of the microwave emission from Uranus is probably caused by changes in the deep tropospheric circulation, because thick polar clouds and haze may inhibit convection. Now that the spring and autumn equinoxes are arriving on Uranus, the dynamics are changing and convection can occur again.

Magnetosphere

Before the arrival of Voyager 2, no measurements of the Uranian magnetosphere had been taken, so its nature remained a mystery. Before 1986, scientists had expected the magnetic field of Uranus to be in line with the solar wind, because it would then align with Uranus's poles that lie in the ecliptic.

Voyager's observations revealed that Uranus's magnetic field is peculiar, both because it does not originate from its geometric centre, and because it is tilted at 59° from the axis of rotation. In fact, the magnetic dipole is shifted from Uranus's centre towards the south rotational pole by as much as one-third of the planetary radius. This unusual geometry results in a highly asymmetric magnetosphere, where the magnetic field strength on the surface in the southern hemisphere can be as low as 0.1 gauss (10 µT), whereas in the northern hemisphere it can be as high as 1.1 gauss (110 µT). The average field at the surface is 0.23 gauss (23 µT).

Studies of Voyager 2 data in 2017 suggest that this asymmetry causes Uranus's magnetosphere to connect with the solar wind once a Uranian day, opening the planet to the Sun's particles. In comparison, the magnetic field of Earth is roughly as strong at either pole, and its "magnetic equator" is roughly parallel with its geographical equator. The dipole moment of Uranus is 50 times that of Earth. Neptune has a similarly displaced and tilted magnetic field, suggesting that this may be a common feature of ice giants. One hypothesis is that, unlike the magnetic fields of the terrestrial and gas giants, which are generated within their cores, the ice giants' magnetic fields are generated by motion at relatively shallow depths, for instance, in the water-ammonia ocean. Another possible explanation for the magnetosphere's alignment is that there are oceans of liquid diamond in Uranus's interior that would deter the magnetic field.

Despite its curious alignment, in other respects the Uranian magnetosphere is like those of other planets: it has a bow shock at about 23 Uranian radii ahead of it, a magnetopause at 18 Uranian radii, a fully developed magnetotail, and radiation belts. Overall, the structure of Uranus's magnetosphere is different from Jupiter's and more similar to Saturn's. Uranus's magnetotail trails behind it into space for millions of kilometres and is twisted by its sideways rotation into a long corkscrew.

Uranus's magnetosphere contains charged particles: mainly protons and electrons, with a small amount of H ₂⁺ ions. Many of these particles probably derive from the thermosphere. The ion and electron energies can be as high as 4 and 1.2 megaelectronvolts, respectively. The density of low-energy (below 1 kiloelectronvolt) ions in the inner magnetosphere is about 2 cm −3. The particle population is strongly affected by the Uranian moons, which sweep through the magnetosphere, leaving noticeable gaps. The particle flux is high enough to cause darkening or space weathering of their surfaces on an astronomically rapid timescale of 100,000 years. This may be the cause of the uniformly dark colouration of the Uranian satellites and rings.

Uranus has relatively well developed aurorae, which are seen as bright arcs around both magnetic poles. Unlike Jupiter's, Uranus's aurorae seem to be insignificant for the energy balance of the planetary thermosphere. In March 2020, NASA astronomers reported the detection of a large atmospheric magnetic bubble, also known as a plasmoid, released into outer space from the planet Uranus, after reevaluating old data recorded by the space probe during a flyby of the planet in 1986.

Uranus has 27 known natural satellites. The names of these satellites are chosen from characters in the works of Shakespeare and Alexander Pope. The five main satellites are Miranda, Ariel, Umbriel, Titania, and Oberon. The Uranian satellite system is the least massive among those of the giant planets; the combined mass of the five major satellites would be less than half that of Triton (largest moon of Neptune) alone. The largest of Uranus's satellites, Titania, has a radius of only 788.9 km (490.2 mi), or less than half that of the Moon, but slightly more than Rhea, the second-largest satellite of Saturn, making Titania the eighth-largest moon in the Solar System. Uranus's satellites have relatively low albedos; ranging from 0.20 for Umbriel to 0.35 for Ariel (in green light). They are ice-rock conglomerates composed of roughly 50% ice and 50% rock. The ice may include ammonia and carbon dioxide.

Among the Uranian satellites, Ariel appears to have the youngest surface, with the fewest impact craters, and Umbriel the oldest. Miranda has fault canyons 20 km (12 mi) deep, terraced layers, and a chaotic variation in surface ages and features. Miranda's past geologic activity is thought to have been driven by tidal heating at a time when its orbit was more eccentric than currently, probably as a result of a former 3:1 orbital resonance with Umbriel. Extensional processes associated with upwelling diapirs are the likely origin of Miranda's 'racetrack'-like coronae. Ariel is thought to have once been held in a 4:1 resonance with Titania.

Uranus has at least one horseshoe orbiter occupying the Sun-Uranus Lagrangian point -a gravitationally unstable region at 180° in its orbit, 83982 Crantor. Crantor moves inside Uranus's co-orbital region on a complex, temporary horseshoe orbit. is also a promising Uranus horseshoe librator candidate.

The Uranian rings are composed of extremely dark particles, which vary in size from micrometres to a fraction of a metre. Thirteen distinct rings are presently known, the brightest being the ε ring. All except the two rings of Uranus are extremely narrow - they are usually a few kilometres wide. The rings are probably quite young; the dynamics considerations indicate that they did not form with Uranus. The matter in the rings may once have been part of a moon (or moons) that was shattered by high-speed impacts. From numerous pieces of debris that formed as a result of those impacts, only a few particles survived, in stable zones corresponding to the locations of the present rings.

William Herschel described a possible ring around Uranus in 1789. This sighting is generally considered doubtful, because the rings are quite faint, and in the two following centuries none were noted by other observers. Still, Herschel made an accurate description of the epsilon ring's size, its angle relative to Earth, its red colour, and its apparent changes as Uranus travelled around the Sun. The ring system was definitively discovered on 10 March 1977 by James L. Elliot, Edward W. Dunham, and Jessica Mink using the Kuiper Airborne Observatory. The discovery was serendipitous; they planned to use the occultation of the star SAO 158687 (also known as HD 128598) by Uranus to study its atmosphere. When their observations were analysed, they found that the star had disappeared briefly from view five times both before and after it disappeared behind Uranus. They concluded that there must be a ring system around Uranus. Later they detected four additional rings. The rings were directly imaged when Voyager 2 passed Uranus in 1986. Voyager 2 also discovered two additional faint rings, bringing the total number to eleven.

In December 2005, the Hubble Space Telescope detected a pair of previously unknown rings. The largest is located twice as far from Uranus as the previously known rings. These new rings are so far from Uranus that they are called the "outer" ring system. Hubble also spotted two small satellites, one of which, Mab, shares its orbit with the outermost newly discovered ring. The new rings bring the total number of Uranian rings to 13. In April 2006, images of the new rings from the Keck Observatory yielded the colours of the outer rings: the outermost is blue and the other one red. One hypothesis concerning the outer ring's blue colour is that it is composed of minute particles of water ice from the surface of Mab that are small enough to scatter blue light. In contrast, Uranus's inner rings appear grey.

Although the Uranian rings are very difficult to directly observe from Earth, advances in digital imaging have allowed several amateur astronomers to successfully photograph the rings with red or infrared filters; telescopes with apertures as small as 36 cm (14 inches) may be able to detect the rings with proper imaging equipment.

Exploration

Main page: Exploration of Uranus

Launched in 1977, Voyager 2 made its closest approach to Uranus on 24 January 1986, coming within 81,500 km (50,600 mi) of the cloudtops, before continuing its journey to Neptune. The spacecraft studied the structure and chemical composition of Uranus's atmosphere, including its unique weather, caused by its axial tilt of 97.77°. It made the first detailed investigations of its five largest moons and discovered 10 new ones. Voyager 2 examined all nine of the system's known rings and discovered two more. It also studied the magnetic field, its irregular structure, its tilt and its unique corkscrew magnetotail caused by Uranus's sideways orientation.

No other spacecraft has flown by Uranus since then, though there have been many proposed missions to revisit the Uranus system. The possibility of sending the Cassini spacecraft from Saturn to Uranus was evaluated during a mission extension planning phase in 2009, but was ultimately rejected in favour of destroying it in the Saturnian atmosphere, as it would have taken about twenty years to get to the Uranian system after departing Saturn. A Uranus entry probe could use Pioneer Venus Multiprobe heritage and descend to 1-5 atmospheres. A Uranus orbiter and probe was recommended by the 2013-2022 Planetary Science Decadal Survey published in 2011; the proposal envisaged launch during 2020-2023 and a 13-year cruise to Uranus. The committee's opinion was reaffirmed in 2022, when a Uranus probe/orbiter mission was placed at the highest priority, due to the lack of knowledge about ice giants.

In astrology, the planet Uranus (symbol ) is the ruling planet of Aquarius. Because Uranus is cyan and Uranus is associated with electricity, the colour electric blue, which is close to cyan, is associated with the sign Aquarius (see Uranus in astrology).

The chemical element uranium, discovered in 1789 by the German chemist Martin Heinrich Klaproth, was named after the then-newly discovered Uranus.

in her 1827 collection of poetry.

"Uranus, the Magician" is a movement in Gustav Holst's orchestral suite The Planets, written between 1914 and 1916.

Operation Uranus was the successful military operation in World War II by the Red Army to take back Stalingrad and marked the turning point in the land war against the Wehrmacht.

The lines "Then felt I like some watcher of the skies/When a new planet swims into his ken", from John Keats's "On First Looking into Chapman's Homer", are a reference to Herschel's discovery of Uranus.

In Spanish: Urano (planeta) para niños

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Kids learn about the planet Jupiter of the Solar System including fun facts, mass, day, year, and distance from the Sun. Astronomy for kids and teachers.

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You're not even close to leaving the solar system when you pull into orbit around Jupiter, but you'd swear you've just entered a new one. Your ship's scanners flash with readings of nearby worlds and faint rings. Jupiter, the largest planet in our solar system, rules a system of its own. Some astronomers consider it a failed star. Welcome to the realm of giants.

Jupiter is a gas giant, a ball of mostly hydrogen and helium large enough to hold more than 1,300 Earths. You won't find any solid surface to explore here, and skydiving from your ship's airlock would be a bad idea. You'd sink deeper into clouds of ammonia and water vapor until the intense atmospheric pressure and heat compressed the hydrogen around you into a molten liquid. Science fiction writers have proposed exploring Jupiter in hot-air balloons high above the crushing depths below, but you're happy sipping cocoa aboard your ship in orbit. It's a safer place to watch Jupiter's spectacular cloud bands whiz by at more than 300 miles an hour (530 kilometers an hour).

Several of Jupiter's nearly 70 moons grab your attention. Mega-moon Ganymede is larger than Mercury and has its own magnetic field. Volcanoes on Io, the most volcanic body in the solar system, spew clouds of yellow sulfur 300 miles (500 kilometers) high. Frozen Europa might hide a liquid ocean beneath its icy crust. Scientists believe Europa might hide something else inside that ocean: life.

MORE FACTS

* Set shields at maximum. Jupiter generates radiation levels more than a thousand times the lethal dose.

* Nearly three Earths could span Jupiter's Great Red Spot, a hurricane that has raged for centuries.

* Jupiter may be the largest planet in the solar system, but it has the shortest day-just 10 hours-because of its rapid rotation.

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Mission to Jupiter - Get facts about this planet

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You're not even close to leaving the solar system when you pull into orbit around Jupiter, but you'd swear you've just entered a new one. Your ship's scanners flash with readings of nearby worlds and faint rings. Jupiter, the largest planet in our solar system, rules a system of its own.

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Quick facts for kidsJupiter

Designations

Jupiter

Adjectives
Jovian

Orbital characteristics

Epoch J2000

Aphelion

816.62 Gm (5.4588 AU)

Perihelion

740.52 Gm (4.9501 AU)

Eccentricity

0.0489

398.88 d

Inclination

Known satellites

80 (as of 2021)

Physical characteristics

69,911 km (43,441 mi)
10.973 Earths

Flattening

0.06487

Volume

Mass

1,326 kg/m³ (2,235 lb/cu yd)

24.79 m/s² (81.3 ft/s ²)
2.528 g

0.2756±0.0006

9.9258 h (9 h 55 m 33 s)

Equatorial rotation velocity

12.6 km/s (7.8 mi/s; 45,000 km/h)

268.057°; 17 h 52 m 14 s

Albedo

0.503 ( Bond)
0.538 ( geometric)

Surface temp.

min

mean

max

1 bar

165 K

0.1 bar

78 K

128 K

1000 K

29.8" to 50.1"

Atmosphere

200-600 kPa (opaque cloud deck)

Composition by volume

Jupiter is the largest planet in the Solar System. It is the fifth planet from the Sun. Jupiter is a gas giant, both because it is so large and made up of gas. The other gas giants are Saturn, Uranus, and Neptune.

Jupiter's mass is 1.8986×10 ²⁷ kg. (318 earths). This is more than twice the mass of all the other planets in the Solar System put together.

Jupiter can be seen even without using a telescope. The ancient Romans named the planet after their King of Gods, Jupiter ( Latin: Iuppiter). Jupiter is the third brightest object in the night sky. Only the Earth's moon and Venus are brighter.

Jupiter has 80 moons. About 50 of them are very small and less than five kilometres wide. The four largest moons of Jupiter are Io, Europa, Ganymede, and Callisto. They are called the Galilean moons, because Galileo Galilei discovered them. Ganymede is the largest moon in the Solar System. It is larger in diameter than Mercury.

Name and symbol

Jupiter was named for the king of the gods. The Greeks called him Zeus. The Romans called him Jupiter. The symbol for Jupiter, , is from the Greek zeta. It has a horizontal stroke⟨Ƶ⟩. This stands as an abbreviation for Zeus.

Jupiter is the biggest planet in the Solar System. Its diameter is 142,984 km. This is eleven times bigger than the diameter of Earth.

Atmosphere

The atmosphere near the surface of Jupiter is about 88 to 92% hydrogen, 8 to 12% helium, and 1% other gases.

The lower atmosphere is so heated and the pressure so high that helium changes to liquid. It rains down onto the planet. Based on spectroscopy, Jupiter seems to be made of the same gases as Saturn. It is different from Neptune or Uranus. Those two planets have much less hydrogen and helium gas.

The very high temperatures and pressures in Jupiter's core mean scientists cannot tell what materials are there. This cannot be found out, because it is not possible to create the same amount of pressure on Earth.

Above the unknown inner core is an outer core. The outer core of Jupiter is thick, liquid hydrogen. The pressure is high enough to make the hydrogen solid, but then it melts because of the heat.

The planet Jupiter is sometimes called a failed star because it is made of the same elements (hydrogen and helium) as is the Sun, but it is not large enough to have the internal pressure and temperature necessary to cause hydrogen to fuse to helium, the energy source that powers the sun and most other stars.

Jupiter is twice as massive as all the other planets in the Solar System put together. It gives off more heat than it gets from the sun. Jupiter is 11 times the width of Earth and 318 times as massive. The volume of Jupiter is 1,317 times the volume of Earth. In other words, 1,317 Earth-sized objects could fit inside it.

Cloud layers

Jupiter has many bands of clouds going horizontally across its surface. The light parts are zones and the darker are belts. The zones and belts often interact with each other. This causes huge storms. Wind speeds of 360 kilometres per hour (km/h) are common on Jupiter. To show the difference the strongest tropical storms on Earth are about 100 km/h.

Most of the clouds on Jupiter are made of ammonia. There may also be clouds of water vapor like clouds on Earth. Spacecrafts such as Voyager 1 have seen lightning on the surface of the planet. Scientists think it was water vapor because lightning needs water vapor. These lightning bolts have been measured as up 1,000 times as powerful as those on Earth. The brown and orange colors are caused when sunlight passes through or refracts with the many gases in the atmosphere.

Great Red Spot

One of the biggest features in Jupiter's atmosphere is the Great Red Spot. It is a huge storm which is bigger than the entire Earth. It is on record since at least 1831, and as early as 1665. Images by the Hubble Space Telescope have shown as many as two smaller "red spots" next to the Great Red Spot. Storms can last for hours or as long as hundreds of years in the case of the Great Red Spot.

Magnetic field

Jupiter has a magnetic field like Earth's but 11 times stronger. It also has a magnetosphere much bigger and stronger than Earth's. The field traps radiation belts much stronger than Earth's Van Allen radiation belts, strong enough to endanger any spacecraft travelling past or to Jupiter. The magnetic field is probably caused by the large amounts of liquid metallic hydrogen in the core of Jupiter. The four largest moons of Jupiter and many of the smaller ones orbit or go around the planet within the magnetic field. This protects them from the solar wind. Jupiter's magnetic field is so large, it reaches the orbit of Saturn 7.7 million miles (12 million km) away. The Earth's magnetosphere does not even cover its moon, less than a quarter of a million miles (400,000 km) away. It also experiences large aurorae, which happen when charged particles from the volcanic moon Io land in its atmosphere.

Ring system

Jupiter also has a thin planetary ring system. These rings are difficult to see and were not discovered until 1979 by NASA's Voyager 1 probe. There are four parts to Jupiter's rings. The closest ring to Jupiter is called the Halo Ring. The next ring is called the Main Ring. It is about 6,440 km (4,002 mi) wide and only 30 km (19 mi) thick. The Main and Halo rings of Jupiter are made of small, dark particles. The third and fourth rings, called the Gossamer Rings, are transparent (see through) and are made from microscopic debris and dust. This dust probably comes from small meteors striking the surface of Jupiter's moons. The third ring is called the Amalthea Gossamer Ring, named after moon Amalthea. The outer ring, the Thebe Gossamer Ring, is named after the moon Thebe. The outer edge of this ring is about 220,000 km (136,702 mi) from Jupiter.

The orbit of a planet is the time and path it takes to go around the Sun. In the amount of time it takes for Jupiter to orbit the Sun one time, the Earth orbits the Sun 11.86 times. One year on Jupiter is equal to 11.86 years on Earth. The average distance between Jupiter and the Sun is 778 million kilometres. This is five times the distance between Earth and the Sun. Jupiter is not tilted on its axis as much as Earth or Mars. This causes it to have no seasons, for example summer or winter. Jupiter rotates, or spins around very quickly. This causes the planet to bulge in the middle. Jupiter is the fastest spinning planet in the Solar System. It completes one rotation or spin in 10 hours. Because of the bulge, the length of the equator of Jupiter is much longer than the length from pole to pole.

Grand tack hypothesis

The orbit of Jupiter is unusual among star systems. It is usual for giant planets to be much nearer to their stars. Because it is not, it suggests an unusual explanation is needed for the arrangement of the planets in the Solar System.

"Over the eons, the giant planet roamed toward the center of the Solar System and back out again, at one point moving in about as close as Mars is now. The planet's travels profoundly influenced the Solar System, changing the nature of the asteroid belt and making Mars smaller than it should have been. These details are based on a new model of the early Solar System developed by an international team that includes NASA's Goddard Space Flight Center in Greenbelt, Md."

Research and exploration

Jupiter is the third brightest object in the night sky, after the Moon and Venus. The first person known to really study the planet was Galileo Galilei in 1610. He was the first person to see Jupiter's moons Io, Europa, Ganymede and Callisto. This was because he used a telescope, unlike anyone before him.

No new moons were discovered for more than two hundred years. In 1892, astronomer E.E Barnard found a new moon using his observatory in California. He called the moon Amalthea. It was the last of Jupiter's 67 moons to be discovered by human observation through a telescope. In 1994, bits of the comet Shoemaker Levy-9 hit Jupiter. It was the first time people saw a collision between two Solar System objects.

From spacecraft

Seven spacecraft have flown past Jupiter since 1973. These were Pioneer 10 (1973), Pioneer 11 (1974), Voyagers 1 and 2 (1979), Ulysses (1992 and 2004), Cassini (2000) and New Horizons (2007).

The Pioneer missions were the first spacecraft to take close up pictures of Jupiter and its moons. Five years later, the two Voyager spacecraft discovered over 20 new moons. They captured photo evidence of lightning on the night side of Jupiter.

The Ulysses probe was sent to study the Sun. It only went to Jupiter after it had finished its main mission. Ulysses had no cameras so it took no photographs. In 2006, the Cassini spacecraft, on its way to Saturn, took some very good, very clear pictures of the planet. Cassini also found a moon and took a picture of it but it was too far away to show the details.

The Galileo mission in 1995 was the first spacecraft to go into orbit around Jupiter. It flew around the planet for seven years and studied the four biggest moons. It launched a probe into the planet to get information about Jupiter's atmosphere. The probe travelled to a depth of about 150 km before it was crushed by the pressure of all the gas above it. The Galileo spacecraft was also crushed in 2003 when NASA steered the craft into the planet. They did this so that the craft could not crash into Europa, a moon which scientists think might have life.

NASA have sent another spacecraft to Jupiter called Juno. It was launched on August 5, 2011 and arrived at Jupiter on July 4, 2016. NASA published some results from the Juno mission in March 2018. Several other missions have been planned to send spacecraft to Jupiter's moons Europa and Callisto. One called JIMO (Jupiter Icy Moons Orbiter) was cancelled in 2006 because it cost too much money.

Jupiter has 80 known moons. The four largest were seen by Galileo with his primitive telescope, and nine more can be seen from Earth with modern telescopes. The rest of the moons have been identified by spacecraft. The smallest moon ( S/2003 J 12) is only one kilometre across. The largest, Ganymede, has a diameter of 5,262 kilometres. It is bigger than the planet Mercury. The other three Galilean moons are Io, Europa and Callisto. Because of the way they orbit Jupiter, gravity affects three of these moons greatly. The friction caused by the gravity of Europa and Ganymede pulling on Io makes it the most volcanic object in the Solar System. It has over 400 volcanoes, more than three times as many as Earth.

Jupiter in the Solar System

Jupiter's large gravity has had an effect on the Solar System. Jupiter protects the inner planets from comets by pulling them towards itself. Because of this, Jupiter has the most comet impacts in the Solar System.

Two groups of asteroids, called Trojan asteroids, have settled into Jupiter's orbit round the Sun. One group is called the Trojans and the other group is called the Greeks. They go around the Sun at the same time as Jupiter.

Images for kids

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Quick facts for kidsJupiter Designations Jupiter Adjectives Jovian Orbital characteristics Epoch J2000 Aphelion 816.62 Gm (5.4588 AU) Perihelion 740.52 Gm (4.9501 AU) Eccentricity 0.0489 398.88 d Inclination Known satellites 80 (as of 2021) Physical characteristics 69,911 km (43,441 mi)10.973 Earths Flattening 0.06487 Volume Mass 1,326 kg/m3 (2,235 lb/cu yd) 24.79 m/s2 (81.3 ft/s 2) 2.528 g 0.2756±0.0006 9.9258 h (9 h 55 m 33 s) Equatorial rotation velocity 12.6 km/s (7.8 mi/s; 45,000 km/h) 268.057°; 17 h 52 m 14 s Albedo 0.503 ( Bond) 0.538 ( geometric) Surface temp.

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Venus means

In astronomy mythology, Venus was the Roman goddess of love and beauty. In Greek, her name was Aphrodite. How much would you weigh on Venus? Because Venus and the Earth are almost the exact same size, you would weigh almost exactly the same on either planet. If you weighed 70 pounds (32 kg) on Earth, you would weigh 63 pounds (29 kg ) on Venus.

The Planet

The planet Venus has long been one of the most misunderstood of all the inner planets. Like the Earth, Venus has an atmosphere. However, Venus' atmosphere is far thicker than that of the Earth, making it difficult for modern science to penetrate. Interestingly, scientists have recently been able to peek through the thick clouds and get a few glimpses of the surface. There are numerous volcanoes and many mountains that appear misshapen.

There is much we still do not know about how this planet looks and what it is like. However, using special instruments and probes scientists have in recent years unlocked many of the secrets long hidden by this mysterious world. In the 1970s, the Soviet Union actually was able to land more than one probe on the surface of Venus. These scientific probes only lasted a few hours before they were destroyed by the intense heat of the planet. These probes were able to take several pictures and send them back to earth for scientists to study.

The Earth Has a Sister

Venus is in many ways Earth's sister planet. It is almost identical in size, chemistry, gravity and density as the Earth. In other words, Venus is made up of almost the exact same types of materials as the Earth and in about the same amounts. Venus has volcanoes, mountains and sand, just like Earth.

However, if they are twins, then Venus is the evil twin; she is the Earth gone wrong, very wrong. Venus is a deadly world where the surface temperature is hot enough to cook a meal in mere minutes. There is nowhere to hide from this ever present furnace. And with the atmosphere containing mostly carbon dioxide, it makes Venus a highly toxic place. No living thing would ever be able to survive on Venus.

Global Warming

In the early days of Venus' 4 billion year long life, it would have appeared very similar to the Earth. The two would have been almost identical. However, over a period of a few million years, forces on Venus caused it to take a very different course than the Earth.

Venus lies much closer to the Sun than does our planet. That single fact has caused an unstoppable chain of events that doomed Venus to its fiery existence. Owing to its closer proximity to the Sun, Venus' temperature should have been only slightly warmer than that of the Earth. But as the planet warmed, the water evaporated. This increase in water vapor in the atmosphere began a cycle of global warming that could not be stopped. Water vapor is a very effective greenhouse gas. (Greenhouse gas soaks up hot air and prevents it from escaping into space). The increase in water vapor caused the temperature to rise further, which caused more water to evaporate, causing the temperature to climb still further.

Today it is likely that all of Venus' water has evaporated into the atmosphere. This atmosphere effectively traps the Sun's energy causing the surface to burn much hotter than it naturally would. The temperatures on Venus can reach almost 900 degrees Fahrenheit (approx 482 degrees Celsius).

Venus is Dry

The Earth has a protective layer known as the Ozone Layer. This important shield protects the Earth from the Sun's ultraviolet radiation. Venus does not have an ozone layer. As a result, the ultraviolet radiation from the Sun finds its way directly into Venus' atmosphere. Over many billions of years this radiation has slowly broken down water molecules into hydrogen and oxygen. As a result, there is today very little water left on Venus.

Geography

Venus has many, many volcanoes. We don't know for sure, but it is possible that Venus has more volcanoes than any of the other planets in our Solar System. But unlike the volcanoes on Earth that can sometimes erupt in an explosive manner, the volcanoes on Venus are believed to erupt in a less violent way. In fact, it is believed that they don't erupt at all. Instead, it is thought that the lava just slowly flows out onto the surface.

Venus has a few mountainous areas along with extensive flat areas. There are craters and evidence that the surface long ago moved, much like the surface of the Earth moves today. But unlike the Earth's surface, there is no evidence that Venus has a tectonic plate system.

From West to East

If you somehow found a way to survive the scorching heat found on the surface of Venus, you would quickly notice something strange about the days. Aside from the fact that Venus rotates very slowly so that a day on Venus lasts more than 100 Earth days, Venus also rotates in the opposite direction as almost all the other planets.

Instead of the Sun rising in the east and setting in the west, the Sun on Venus would appear to rise in the west and set in the east.

Moons

Venus has no moons.

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Venus means In astronomy mythology, Venus was the Roman goddess of love and beauty. In Greek, her name was Aphrodite. How much would you weigh on Venus? Because Venus and the Earth are almost the exact same size, you would weigh almost exactly the same on either planet.

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Kids learn about the planet Venus of the Solar System including fun facts, mass, day, year, and distance from the Sun. Astronomy for kids and teachers.

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You expected to find seas, mountains-maybe even a few trees-on a planet considered "Earth's twin." Instead, Venus is like Earth in reverse. A day here lasts longer than a year, the sun rises in the west and sets in the east, and-whew!-is it ever hot outside! Venus' average temperature is more than six times hotter than the hottest spot on Earth. That's hot enough to turn a slab of lead into a molten puddle. Sunset won't bring relief from the scorching heat. Day or night, from its north pole to its south pole, every day of the year, Venus is locked in a perpetual heat wave. Blame the blanketing atmosphere, more than 90 times thicker than Earth's, of carbon dioxide. Good thing your spacesuit has air conditioning!

How did such a harsh planet earn the title of Earth's twin? Venus is roughly the same size and density as Earth, which means the gravity is similar between here and home. The view from the scalding surface isn't all that alien, either. Like Earth, Venus has clouds and wind-although the clouds are made of sulfuric acid and the wind exceeds tornado strength. The sunlight filtering from above bathes the landscape in a dim red glow. You'll never spot Earth through those heavy clouds, but rest assured that your friends back home can see you. Venus is the brightest object in Earth's sky after the moon.

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You expected to find seas, mountains-maybe even a few trees-on a planet considered "Earth's twin." Instead, Venus is like Earth in reverse. A day here lasts longer than a year, the sun rises in the west and sets in the east, and-whew!-is it ever hot outside!

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You've probably used the word "awesome" a hundred times to describe anything from the graphics in a new video game to the jelly filling in your favorite donut, but you never knew the word's true meaning until you pull into the shade of Saturn's rings. More than 155,000 miles (250,000 kilometers) wide, dappled with spokes that rotate at different rates, Saturn's awe-inspiring ring system is the most complex of all the planets. If Earth is the jewel in the solar system, then Saturn wears the crown.

The rings lose none of their luster when seen up close. What appears as a solid disc from a distance is actually a glittering shower of ice and rock. And although the rings stretch almost as far into space as the distance between the Earth and the moon, they're incredibly thin-typically about 30 feet (10 meters) wide. Astronomers believe Saturn's rings formed from bits of asteroids and comets that shattered before they reached the planet. Swoop low over Saturn's atmosphere and you might watch two of the planet's moons rise within gaps in the rings.

You couldn't watch this moonrise from the planet's surface, though. Like Jupiter, Uranus, and Neptune, Saturn is a gas giant, a ball of mostly hydrogen and helium more than 750 times the size of Earth. Its yellow color comes from ammonia crystals in the upper atmosphere, which is home to electrical storms the size of the United States. Steer clear of those lightning strikes. They're a thousand times more powerful than Earth's. And, yes, they're awesome.

MORE FACTS

* Saturn is the only planet in the solar system that's less dense than water-which means it would float if you dunked it in a large enough ocean.

* Titan, one of Saturn's 53 moons and its largest, has an atmosphere of mostly nitrogen similar to ancient Earth's.

* A small moon named Mimas sports an impact crater that makes it look just like the Death Star from Star Wars.

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Mission to Saturn - Get facts about this planet

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You've probably used the word "awesome" a hundred times to describe anything from the graphics in a new video game to the jelly filling in your favorite donut, but you never knew the word's true meaning until you pull into the shade of Saturn's rings.

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Quick facts for kidsSaturn

Designations

Adjectives

Saturnian

Orbital characteristics

Epoch J2000

Aphelion

1,513,325,783 km
10.115 958 04 AU

Perihelion

1,353,572,956 km
9.048 076 35 AU

1,433,449,370 km
9.582 017 20 AU

Eccentricity

0.055 723 219

10,832.327 days
29.657 296 yr

Inclination

2.485 240° to Ecliptic
5.51° to Sun's equator
0.93° to Invariable plane

Known satellites

around 200 observed (61 with secure orbits)

Physical characteristics

58,232±6 km

Flattening

0.097 96 ± 0.000 18

4.27×10 ¹⁰ km ²
83.703 Earths

Volume

8.2713×10 ¹⁴ km ³
763.59 Earths

Mass

5.6846×10 ²⁶ kg
95.152 Earths

0.687 g/cm ³
(less than water)

10,44 m/s²
0.914g

0.439-0.449 days
(10 h 32 - 47 min)

Equatorial rotation velocity

9.87 km/s
35 500 km/h

2 h 42 min 21 s
40.589°

Albedo

0.342 bond
0.47 geom

Surface temp.

min

mean

max

1 bar level

134 K

0.1 bar

84 K

14.5" - 20.1"
(excludes rings)

Atmosphere

Composition by volume

~96% hydrogen (H ₂)
Ices:
ammonia
water
ammonium hydrosulfide (NH ₄ SH)

Saturn is the sixth planet from the Sun in the Solar System. It is the second largest planet in the Solar System, after Jupiter. Like Jupiter, Uranus and Neptune, it is a " gas giant".

Inside Saturn is probably a core of iron, nickel, silicon and oxygen compounds, surrounded by a deep layer of metallic hydrogen, then a layer of liquid hydrogen and liquid helium and finally, an outer gaseous layer.

Saturn has 62 known moons orbiting the planet; 53 are officially named. The largest moon is Titan, which is larger in volume than the planet Mercury. Titan is the second-largest moon in the Solar System. The largest moon is Jupiter's moon, Ganymede. There is also a very large system of rings around Saturn. These rings are made of ice with smaller amounts of rocks and dust. Saturn is about 1,400,000,000 km (869,000,000 mi) from the Sun. Saturn takes 29.6 years on Earth to revolve around the Sun.

Saturn was named after the Roman god Saturnus (called Kronos in Greek mythology). Saturn's symbol is ♄ which is the symbol of Saturnus' sickle.

Physical features

Saturn is an oblate spheroid, meaning that it is flattened at the poles, and it swells out around its equator. The planet's equatorial diameter is 120,536 km (74,898 mi), while its polar diameter (the distance from the north pole to the south pole) is 108,728 km (67,560 mi); a 9% difference. Saturn has a flattened shape; it is due to its very fast rotation, rotating once every 10.8 hours. Saturn is the only planet in the Solar System that is less dense than water. Even though the planet's core is very dense, it has a gaseous atmosphere, so the average specific density of the planet is 0.69 g/cm ³ (less than the density of water). This means if Saturn could be placed in a large pool of water, it would float.

Atmosphere

The outer part of Saturn's atmosphere is made up of about 96% hydrogen, 3% helium, 0.4% methane and 0.01% ammonia. There are also very small amounts of acetylene, ethane and phosphine.

Saturn's clouds show a banded pattern, like the cloud bands seen on Jupiter. Saturn's clouds are much fainter and the bands are wider at the equator. Saturn's lowest cloud layer is made up of water ice, and is about 10 km (6 mi) thick. The temperature here is quite low, at 250 K (-10° F, -23° C). However scientists do not agree about this. The layer above, about 77 km (48 mi) thick, is made up of ammonium hydrosulfide ice, and above that is a layer of ammonia ice clouds 80 km (50 mi) thick. The highest layer is made up of hydrogen and helium gases, which extends between 200 km (124 mi) and 270 km (168 mi) above the water cloud tops. Auroras are also known to form in Saturn in the mesosphere. The temperature at Saturn's cloud tops is extremely low, at 98 K (-283°F, -175°C). The temperatures in the inner layers are much higher than the outside layers because of the heat produced by Saturn's interior. Saturn's winds are some of the fastest in the Solar System, reaching 1,800 km/h (1,118 mph), ten times faster than winds on Earth.

Storms and spots

Saturn's atmosphere is also known to form oval shaped clouds, similar to the clearer spots seen in Jupiter. These oval spots are cyclonic storms, the same as cyclones seen on Earth. In 1990, the Hubble Space Telescope found a very large white cloud near Saturn's equator. Storms like the one in 1990 were known as Great White Spots. These unique storms only exist for a short time and only happen about every 30 Earth years, at the time of the summer solstice in the Northern Hemisphere. Great White Spots were also found in 1876, 1903, 1933, and 1960. If this cycle continues, another storm will form in about 2020.

The Voyager 1 spacecraft found a hexagonal cloud pattern near Saturn's north pole at about 78°N. The Cassini−Huygens probe later confirmed it in 2006. Unlike the north pole, the south pole does not show any hexagonal cloud feature. The probe also discovered a hurricane-like storm locked to the south pole that clearly showed an eyewall. Until this discovery, eyewalls had only been seen on Earth.

Saturn's interior is similar to Jupiter's interior. It has a small rocky core about the size of the Earth at its centre. It is very hot; its temperature reaches 15,000 K (26,540 °F (14,727 °C)). Saturn is so hot that it gives out more heat energy into space than it receives from the Sun. Above it is a thicker layer of metallic hydrogen, about 30,000 km (18,641 mi) deep. Above that layer is a region of liquid hydrogen and helium. The core is heavy, with about 9 to 22 times more mass than the Earth's core.

Magnetic field

Saturn has a natural magnetic field that is weaker than Jupiter's. Like the Earth's, Saturn's field is a magnetic dipole. Saturn's field is unique in that it is perfectly symmetrical, unlike any other known planet. This means the field is exactly in line with the planet's axis. Saturn generates radio waves, but they are too weak to be detected from Earth. The moon Titan orbits in the outer part of Saturn's magnetic field and gives out plasma to the field from the ionised particles in Titan's atmosphere.

Rotation and orbit

Saturn's average distance from the Sun is over 1,400,000,000 km (869,000,000 mi), about nine times the distance from the Earth to the Sun. It takes 10,759 days, or about 29.7 years, for Saturn to orbit around the Sun. This is known as Saturn's orbital period.

Voyager 1 measured Saturn's rotation as being 10 hours 14 minutes at the equator, 10 hours 40 minutes closer to the poles, and 10 hours 39 minutes 24 seconds for the planet's interior. This is known as its rotational period.

Cassini measured the rotation of Saturn as being 10 hours 45 minutes 45 seconds ± 36 seconds. That is about six minutes, or one percent, longer than the radio rotational period measured by the Voyager 1 and Voyager 2 spacecraft, which flew by Saturn in 1980 and 1981.

Saturn's rotational period is calculated by the rotation speed of radio waves released by the planet. The Cassini−Huygens spacecraft discovered that the radio waves slowed down, suggesting that the rotational period increased. Since the scientists do not think Saturn's rotation is actually slowing down, the explanation may lie in the magnetic field that causes the radio waves.

Planetary rings

Saturn is best known for its planetary rings which are easy to see with a telescope. There are seven named rings; A, B, C, D, E, F, and G rings. They were named in the order they were discovered, which is different to their order from the planet. From the planet the rings are: D, C, B, A, F, G and E.

Scientists believe that the rings are the material left after a moon broke apart. A new idea says that it was a very large moon, most of which crashed into the planet. This left a large amount of ice to form the rings, and also some of the moons, like Enceladus, which are thought to be made of ice.

The rings were first discovered by Galileo Galilei in 1610, using his telescope. They did not look like rings to Galileo, so he called them "handles". He thought that Saturn was three separate planets that almost touched one another. In 1612, when the rings were facing edge on with the Earth, the rings disappeared, then reappeared again in 1613, further confusing Galileo. In 1655, Christiaan Huygens was the first person to recognise Saturn was surrounded by rings. Using a much more powerful telescope than Galilei's, he noted Saturn "is surrounded by a thin, flat, ring, nowhere touching...". In 1675, Giovanni Domenico Cassini discovered that the planet's rings were in fact made of smaller ringlets with gaps. The largest ring gap was later named the Cassini Division. In 1859, James Clerk Maxwell showed that the rings cannot be solid, but are made of small particles, each orbiting Saturn on their own, otherwise, it would become unstable or break apart. James Keeler studied the rings using a spectroscope in 1895 which proved Maxwell's theory.

Physical features

The rings range from 6,630 km (4,120 mi) to 120,700 km (75,000 mi) above the planet's equator. As proved by Maxwell, even though the rings appear to be solid and unbroken when viewed from above, the rings are made of small particles of rock and ice. They are only about 10 m (33 ft) thick; made of silica rock, iron oxide and ice particles. The smallest particles are only specks of dust while the largest are the size of a house. The C and D rings also seem to have a "wave" in them, like waves in water. These large waves are 500 m (1,640 ft) high, but only moving slowly at about 250 m (820 ft) each day. Some scientists believe that the wave is caused by Saturn's moons. Another idea is the waves were made by a comet hitting Saturn in 1983 or 1984.

The largest gaps in the rings are the Cassini Division and the Encke Division, both visible from the Earth. The Cassini Division is the largest, measuring 4,800 km (2,983 mi) wide. However, when the Voyager spacecrafts visited Saturn in 1980, they discovered that the rings are a complex structure, made out of thousands of thin gaps and ringlets. Scientists believe this is caused by the gravitational force of some of Saturn's moons. The tiny moon Pan orbits inside Saturn's rings, creating a gap within the rings. Other ringlets keep their structure due to the gravitational force of shepherd satellites, such as Prometheus and Pandora. Other gaps form due to the gravitational force of a large moon farther away. The moon Mimas is responsible for clearing away the Cassini gap.

Recent data from the Cassini spacecraft has shown that the rings have their own atmosphere, free from the planet's atmosphere. The rings' atmosphere is made of oxygen gas, and it is produced when the Sun's ultraviolet light breaks up the water ice in the rings. Chemical reaction also occurs between the ultraviolet light and the water molecules, creating hydrogen gas. The oxygen and hydrogen atmospheres around the rings are very widely spaced. As well as oxygen and hydrogen gas, the rings have a thin atmosphere made of hydroxide. This anion was discovered by the Hubble Space Telescope.

The Voyager space probe discovered features shaped like rays, called spokes. These were also seen later by the Hubble telescope. The Cassini probe photographed the spokes in 2005. They are seen as dark when under sunlight, and appear light when against the unlit side. At first it was thought the spokes were made of microscopic dust particles but new evidence shows that they are made of ice. They rotate at the same time with the planet's magnetosphere, therefore, it is believed that they have a connection with electromagnetism. However, what causes the spokes to form is still unknown. They appear to be seasonal, disappearing during solstice and appearing again during equinox.

Saturn has 53 named moons, and another nine which are still being studied. Many of the moons are very small: 33 are less than 10 km (6 mi) in diameter and 13 moons are less than 50 km (31 mi). Seven moons are large enough to be a near perfect sphere caused by their own gravitation. These moons are Titan, Rhea, Iapetus, Dione, Tethys, Enceladus and Mimas. Titan is the largest moon, larger than the planet Mercury, and it is the only moon in the Solar System to have a thick, dense atmosphere. Hyperion and Phoebe are the next largest moons, larger than 200 km (124 mi) in diameter.

In December 2004 and January 2005 a man-made satellite called the Cassini−Huygens probe took lots of close photos of Titan. One part of this satellite, known as the Huygens probe, then landed on Titan. Named after the Dutch astronomer Christiaan Huygens, it was the first spacecraft to land in the outer Solar System. The probe was designed to float in case it landed in liquid. Enceladus, the sixth largest moon, is about 500 km (311 mi) in diameter. It is one of the few outer solar system objects that shows volcanic activity. In 2011, scientists discovered an electric link between Saturn and Enceladus. This is caused by ionised particles from volcanos on the small moon interacting with Saturn's magnetic fields. Similar interactions cause the northern lights on Earth.

Exploration

Saturn was first explored by the Pioneer 11 spacecraft in September 1979. It flew as close as 20,000 km (12,427 mi) above the planet's cloud tops. It took photographs of the planet and a few of its moons, but were low in resolution (the quality was not very good). It discovered a new, thin ring called the F ring. It also discovered that the dark ring gaps appear bright when viewed towards the Sun, which shows the gaps are not empty of material. The spacecraft measured the temperature of the moon Titan.

In November 1980, Voyager 1 visited Saturn, and took higher resolution photographs of the planet, rings and moons. These photos were able to show the surface features of the moons. Voyager 1 went close to Titan, and gained much information about its atmosphere. In August, 1981, Voyager 2 continued to study the planet. Photos taken by the space probe showed that changes were happening to the rings and atmosphere. The Voyager spacecrafts discovered a number of moons orbiting close to Saturn's rings, as well as discovering new ring gaps.

On July 1, 2004, the Cassini−Huygens probe entered into orbit around Saturn. Before then, it flew close to Phoebe, taking very high resolution photos of its surface and collecting data. On December 25, 2004, the Huygens probe separated from the Cassini probe before moving down towards Titan's surface and landed there on January 14, 2005. It landed on a dry surface, but it found that large bodies of liquid exist on the moon. The Cassini probe continued to collect data from Titan and a number of the icy moons. It found evidence that the moon Enceladus had water erupting from its geysers. Cassini also proved, in July 2006, that Titan had hydrocarbon lakes, located near its north pole. In March 2007, it discovered a large hydrocarbon lake the size of the Caspian Sea near its north pole.

Cassini observed lightning occurring in Saturn since early 2005. The power of the lightning was measured to be 1,000 times more powerful than lightning on Earth. Astronomers believe that the lightning observed in Saturn is the strongest ever seen.

Related pages

Images for kids

Methane bands circle Saturn. The moon Dione hangs below the rings to the right.

Possible beginning of a new moon (white dot) of Saturn (image taken by Cassini on 15 April 2013)

Galileo Galilei observed the rings of Saturn in 1610, but was unable to determine what they were

Saturn eclipses the Sun, as seen from Cassini. The rings are visible, including the F Ring.

In Spanish: Saturno (planeta) para niños

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Kids learn about the planet Saturn of the Solar System including its rings, mass, day, year, and distance from the Sun. Astronomy for kids and teachers.

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Don't panic when you peer from the porthole of your spaceship as it plummets to the surface of Mercury: You haven't taken a wrong turn and touched down on the moon. Cratered, contoured with hills, and covered with dark dust, Mercury's landscape certainly looks a lot like the moon's. This itty-bitty planet-the smallest in the solar system-is only slightly larger than our moon, too. But one look up from Mercury's surface at high noon will tell you you're far from home. Seen from here, the sun appears three times larger in the sky than it does when viewed from Earth. You're standing on the closest planet to the sun. Forget your sunglasses? Okay, now you can panic.

Mercury is a planet of extremes. By day (which actually lasts roughly 30 Earth days), it's one of the solar system's most scorching spots-more than four times hotter than boiling water. By night, temperatures plummet hundreds of degrees below freezing. (The planet's weak gravity can't keep a grip on a heat-trapping atmosphere.) But despite its harsh environment, this hot-and-cold rock offers perks for the spacefarer. A weak magnetic field protects visitors from the sun's deadly solar radiation ( Earth has a similar but much stronger field), and the crater-pocked surface may contain valuable minerals. The speediest of all the planets, Mercury orbits the sun every 88 days-which means any Earthlings born here could celebrate four birthdays for your every one.

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Don't panic when you peer from the porthole of your spaceship as it plummets to the surface of Mercury: You haven't taken a wrong turn and touched down on the moon. Cratered, contoured with hills, and covered with dark dust, Mercury's landscape certainly looks a lot like the moon's.

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Kids learn about the planet Mercury of the Solar System including fun facts, mass, day, year, and distance from the Sun. Astronomy for kids and teachers.

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Mercury means

In astronomy mythology, Mercury was the Roman version of the Greek god Hermes. He was the messenger for the other gods, and for this reason Mercury is often depicted in pictures with winged sandals. In addition to delivering messages, he was also the protector of travelers and merchants.

How much would you weigh on Mercury?

If you moved to Mercury you would not weigh as much as you do on Earth. Not because you would lose weight on the spaceship, but because Mercury is smaller, and so has less gravity. If you weigh 70 pounds (32 kg) on Earth, you would weigh only about 27 pounds (12 kg) on Mercury.

The Planet

The planet Mercury is the closest of the planets to the Sun. Because this planet lies so close to the Sun, and as a result somewhat near to Earth, it is visible to observers on Earth in the late evening or early morning sky. Because of this, Mercury has become a part of the mythology and legend of almost every culture throughout the history of the Earth.

This planet is often called a morning star. This is because Mercury shines brightly in the early morning just before the sun rises. It has also been called an evening star for the same reason. Mercury is often visible for a brief period of time just after the Sun sets.

Mercury is Heavy

Because of its proximity to the Sun, Mercury's evolution took a slightly different course than that of the other planets. As the Sun formed, it pushed much of the lighter gas and dust out of the inner Solar System, leaving behind only heavier elements. As a result, Mercury is made out of a large percentage of heavier elements, mainly iron. It is essentially a large metal ball of iron with a very thin silicate crust. Mercury's core makes up about 75% of the planet. Its thin mantle, or crust, is only about 300 to 400 miles thick (500 to 600 km). Next to Earth, Mercury is the second most dense planet in our Solar System.

Mercury Has Wrinkles

As Mercury's iron core cooled it contracted, or shrunk. This caused its rocky crust to become wrinkled. Scientists call these wrinkles Lobate Scarps. This scarps can be hundreds of miles long and even up to a mile high. Mercury's core has not cooled completely, however. Researcher recently found evidence that Mercury has a molten core.

Mercury is Scarred

The surface of the planet Mercury is covered with craters. These craters have been created by eons of accidental encounters with asteroids and comets. All celestial bodies within the Solar System are subject to these bombardments. However, many of the planets have the ability to heal themselves through natural geological processes.

Because Mercury's crust is so thick and hard, no volcanic activity can make its way through to the surface of the planet. Since this surface volcanic activity cannot happen, Mercury will forever retain its scars.

Mercury Has No Atmosphere

The planet Mercury is too small and has too little gravity to hold onto an atmosphere. Any gases released from the planet quickly escape into space. Also, Mercury is so close to the Sun that any atmosphere is quickly blown away by the Sun's solar winds. That means that there is almost no air on Mercury.

Temperature Extremes

Mercury is just a little bit larger than Earth's moon. The surface of Mercury that faces the Sun can reach about 800 degrees Fahrenheit. On the other hand, the temperature on the nighttime side can plummet to almost -300 degrees Fahrenheit. This is because Mercury has little to no atmosphere to help regulate temperature.

Time on Mercury

Because of its close location to the Sun, the planet Mercury has become tidally locked to the Sun, or nearly so. The tidal forces of the Sun have over eons of time slowed down the rotation of Mercury to match its revolution around the Sun. The result is that Mercury rotates very slowly. One day on Mercury is about 58-1/2 Earth days long. But while Mercury's days are very long, its revolution around the Sun is rather fast. Mercury can complete one orbit around the Sun in only 88 Earth days. That's just about 3 months here on Earth. This is why Mercury's name is so appropriate. In mythology, Mercury was a speedy messenger, just like the planet's speedy revolution around the Sun.

Moons

Mercury has no moons.

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Mercury means In astronomy mythology, Mercury was the Roman version of the Greek god Hermes. He was the messenger for the other gods, and for this reason Mercury is often depicted in pictures with winged sandals. In addition to delivering messages, he was also the protector of travelers and merchants.

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Kids learn about the planet Mars of the Solar System including fun facts, mass, day, year, and distance from the Sun. Astronomy for kids and teachers.

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Mars means

Mars was the Roman god of war and agriculture. It may not seem like these two things go together, but they do. Mars protected those who fought for their communities, and stayed home to raise crops for food. In Greek, Mars was known as Ares.

How much would you weigh on Mars?

If you weighed 70 pounds (32 kg) on the Earth, you would weigh about 27 pounds (12 kg) on Mars.

The Planet

Mars excites scientists because its mild temperament is more like the Earth's than any of the other planets. Evidence suggests that Mars once had rivers, streams, lakes, and even an ocean. As Mars' atmosphere slowly depleted into outer space, the surface water began to permanently evaporate. Today the only water on Mars in either frozen in the polar caps or underground.

You may sometimes hear Mars referred to as the "Red Planet." This is because the surface of Mars is red. If you stood on the surface of Mars, you would see red dirt and rocks everywhere.

Exploration

At first, the only way modern explorers could study Mars was with satellites that would fly close to the surface of Mars and take pictures as it did so. The satellites would then send these pictures back to Earth.

As scientific technology became more advanced, scientists were able to put spacecraft into orbit around the Red Planet. These types of missions allowed scientists and researchers to obtain even more information about Mars.

Then, as technology advanced even more, scientists and researchers were able to actually land spacecraft on the surface of Mars. To learn more about these amazing explorations, Click Here.
What if humans went to Mars?
Moons

Mars has two moons, their names are Deimos and Phobos. To learn about these worlds, Click Here.

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Mars means Mars was the Roman god of war and agriculture. It may not seem like these two things go together, but they do. Mars protected those who fought for their communities, and stayed home to raise crops for food. In Greek, Mars was known as Ares.

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LOCATION: Fourth rock from the sun

DISTANCE FROM THE SUN: 128,409,598 to 154,865,853 miles (206,669,000 to 249,209,300 kilometers)

AVERAGE SURFACE TEMPERATURE: -81° F (-63° C)

LENGTH OF SPACE JOURNEY FROM EARTH TO MARS: 7 months

GRAVITY: If you weigh 100 pounds (45 kilograms) on Earth, you'd weigh 38 pounds (17 kilograms) here.

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Mission to Mars - Get facts about this planet

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Get the facts on Mars, also known as the red planet.

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Fun planet facts for kids including photos; suitable for Kindergarten through Grade 6.

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Solar System Facts for Kids | Planets for Kids | Geography | Quiz

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Our Solar System Facts for Kids will provide interesting and fun facts about planets of our Sun. And here you will find our link to the solar systems quiz

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The Planets for Kids | Solar System Facts for Kids

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Explore the nine (or eight) planets of our solar system with easy-to-understand information for kids.

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There are eight planets in our Solar System. Pluto used to be called a planet, but in August 2006, the International Astronomical Union decided it was a dwarf planet instead. There are four more known dwarf planets in the Solar System, Ceres, Makemake, Eris and Haumea.