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Using the Matariki star cluster as a context for learning can cover many different subjects.

Stars

There are about a thousand stars in Matariki (also known as the Pleiades), but only about seven are visible to the unaided eye:

Alcyone - Matariki, eyes of Tāwhirimātea

Atlas - Tupu-ā-rangi, sky tohunga

Electra - Waipuna-ā-rangi, sky spring

Taygeta - Waitī, sweet water

Pleione - Tupu-ā-nuku, Earth tohunga

Merope - Ururangi, entry to the heavens

Maia - Waitā, sprinkle of water

The relatively young 'teenage' stars were born together in a nebula at about the same time. They are much larger than our Sun and are blue because they are hot. Blue stars are the hottest, yellow are medium hot and red stars are at the cooler end of the spectrum.

The hazy white light around the stars that can be seen with a telescope was thought to be the remnants of the nebula the stars came from. However, scientists have discovered that the stars are a little too old to still have remains of the molecular cloud. The hazy light connecting the stars together is a nebula the stars are passing through - the Merope nebula.

The Pleiades is one of the nearest star clusters to Earth - it's just 444.2 light years away. The distance to the Pleiades is used by astronomers as a marker to help calculate distances to other stars. However, measuring the distance has not been without controversy with two different mechanisms measuring two different measurements. Read more in this article: Resolving the Pleiades distance problem.

Orbit

Matariki is celebrated on the day of the first crescent moon after the reappearance of Matariki, which is why it isn't on the same day every year. Matariki is visible almost all year, except for right before the Matariki festival starts. This is because, from our perspective on Earth, Matariki is behind the Sun.

Matariki is used to reset the Maori calendar, which is a lunar calendar. The cycle of the Moon around Earth is different to the cycle of Earth around the Sun. The Moon cycle is around 11 days shorter than the solar cycle, meaning that, after 12 months, there is still about 11 days until Earth returns to the same position in its orbit. Stars can be used to reset the lunar calendar because they are in the same place in the sky at the same time in Earth's orbit.

Culture

Matariki is visible in many locations so has lots of names across different cultures. The Greek name is the Pleiades, in Japan it is called Subaru and in China it is Mao, the Hairy Head of the White Tiger of the West.

Māori ancestors possessed a wealth of astronomical knowledge that they referred to as tātai arorangi. Maori use the stars and moon as a calendar with each phase of the Moon indicating the favourable times for planting, fishing or eeling.

Stargazing

After Matariki, the star cluster gets easier to see as it rises earlier and earlier in the morning, then later and later at night. The cluster can be found by looking north-east after the festival of Matariki - find Orion's Belt and follow the three stars across the sky to the left until you find Matariki. Once you find it the first time, you'll always be able to spot it because of its distinctive grouping. This makes it a great class stargazing exercise.

Related content

Acknowledgement

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Using the Matariki star cluster as a context for learning can cover many different subjects.

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Uncovering our explosive past

How do volcanoes work? Where do they form? And what does this mean for the people that live around them?

This resource provides explanations of the key concepts encountered when investigating volcanoes - the 'basics' that every student should understand.

Volcano types

A caldera is a type of giant volcanic crater that forms following a violent eruption that resulted in vast amounts of magma being emptied and leaving a void space that later collapsed. The subsequent depression or hole is often filled with water to form a lake. Examples are Lake Taupō and Lake Rotorua. Calderas are often associated with high-gas rhyolite magmas.

A cone volcano has steep sides and often a vent at the top and is also referred to as a stratovolcano. It is formed by many eruptions over a period of time, generally of andesite magma. Mt Taranaki and Mt Ruapehu are examples of cone volcanoes.

Shield volcanoes are often formed from a large diffuse area of low viscosity basaltic magma that forces its way through the crust at different points. This results in a large number of inactive volcanoes within a relatively small geographical region. Although each volcano is dormant, the field may remain active, and magma can push through and form another new volcano at another point.

Volcanic rock types

Rhyolite contains more than 70% silica and little iron so it is not heavy, and it is often white in colour (for example, pumice). Magma that contains rhyolite is generally cool (750-850ºC) in temperature as it emerges and quite thick. When rhyolitic magma erupts and contains only low amounts of gas, it forms viscous lava flows and domes (for example, Mt Maunganui). Usually it is associated with high amounts of gas, which cause highly explosive eruptions (Taupō eruptions). Rhyolite is often associated with caldera volcanoes.

Andesite contains moderate amounts of silica (between 55-70%) and some iron. Magma that contains andesite is generally around 800-1,000ºC and forms steep-sided cone volcanoes (stratovolcanoes). Mt Ngāuruhoe is an example of an andesite volcano.

Basalt contains not much silica (less than 50%) but a lot of iron so it is heavy and dark in colour. Magma that contains basalt is generally over 1,200ºC and runny. It forms shallow-sided volcanoes (shield volcanoes) or craters and is associated with volcanic fields. Rangitoto Island is an example of a basalt volcano.

Tephra

The collective term for all airborne volcanic material is (commonly called ash). Ash is the smallest component of tephra (material less than 2 mm), lapilli is slightly larger (2-64 mm), and the largest fragments are called blocks and bombs (larger than 64 mm).

Volcanic field

An area of volcanoes that is not associated with a tectonic plate boundary, for example, the Auckland volcanic field. The area is associated with a 'hot spot' in the Earth's mantle that causes the crust to melt slightly, forming a reservoir of magma. There is no single vent for the magma, which results in many volcanoes, and each eruption generally happens in a different place. Volcanic fields have a lot of inactive volcanoes spread over a particular area. They are associated with shield volcanoes like Mount Kilauea on Hawaii.

Subduction zone

An area where one tectonic plate is being forced under another. In a subduction zone, the plates melt and often form a pool of magma. This is often associated with volcanism. The ring of fire around the Pacific - a zone of pronounced volcanic activity - is also the edge of the Pacific plate. These areas are also often associated with frequent earthquakes.

Volcanic hazard

The chance of a volcanic eruption occurring. Scientists evaluate historical data to identify what sort of eruptions occurred and find out which part of the country might be expected to experience a volcanic eruption. They investigate what area would be affected, how much ash might be produced and how long an eruption would last to help define the volcanic hazard.

Risk of volcanic eruption

The combination of a volcanic hazard and the overall effect that the hazard has on a population of people. The risk posed by a volcano is determined by the probability of an eruption, how big that eruption would be and how people would respond. If people are well prepared, the overall risk posed by an eruption is decreased, but the risk increases if people are not prepared. The best way to reduce the risks associated with volcanoes is to be prepared for a possible eruption.

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How do volcanoes work? Where do they form? And what does this mean for the people that live around them? This resource provides explanations of the key concepts encountered when investigating volcanoes - the 'basics' that every student should understand.

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(Image credit: MARK GARLICK/SCIENCE PHOTO LIBRARY via Getty Images)

The order of the planets in the solar system, starting nearest the sun and working outward is the following: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and then the possible Planet Nine.

The solar system extends from the sun, goes past the four inner planets, through the asteroid belt to the four gas giants and on to the disk-shaped Kuiper Belt and far beyond to the teardrop-shaped heliopause.

Scientists estimate that the edge of the solar system is about 9 billion miles (15 billion kilometers) from the sun. Beyond the heliopause lies the giant, spherical Oort Cloud, which is thought to surround the solar system.
Related: 10 incredible volcanoes in our solar system
Ever since the discovery of Pluto in 1930, kids grew up learning that the solar system has nine planets. That all changed in the late 1990s when astronomers started arguing about whether Pluto was indeed a planet. In a highly controversial decision, the International Astronomical Union ultimately decided in 2006 to designate Pluto as a "dwarf planet," reducing the list of the solar system's true planets to just eight.

If you insist on including Pluto, it would come after Neptune on the list. Pluto is truly way out there and on a wildly tilted, elliptical orbit (two of the several reasons it was demoted).
Related: 15 stunning places on Earth that look like they're from another planet
Astronomers, however, are still hunting for another possible planet in our solar system, a true ninth planet, after mathematical evidence of its existence was revealed on Jan. 20, 2016. The alleged "Planet Nine," also called "Planet X," is believed to be about 10 times the mass of Earth and 5,000 times the mass of Pluto.

Types of planets in the solar system

The inner four planets closest to the sun - Mercury, Venus, Earth and Mars - are often called the " terrestrial planets" because their surfaces are rocky. Pluto also has a rocky, albeit frozen, surface but has never been grouped with the four terrestrials.

The four large outer worlds - Jupiter, Saturn, Uranus and Neptune - are sometimes called the Jovian or "Jupiter-like" planets because of their enormous size relative to the terrestrial planets. They're also mostly made of gases like hydrogen, helium and ammonia rather than of rocky surfaces, although astronomers believe some or all of them may have solid cores.

Jupiter and Saturn are sometimes called the gas giants, whereas the more distant Uranus and Neptune have been nicknamed the ice giants. This is because Uranus and Neptune have more atmospheric water and other ice-forming molecules, such as methane, hydrogen sulfide and phosphene, that crystallize into clouds in the planets' frigid conditions, according to the Planetary Society. For perspective, methane crystallizes at minus 296 Fahrenheit (minus 183 degrees Celsius), according to the U.S. National Library of Medicine.

Solar system FAQs answered by an expert

We asked Maximilian Guenther, ESA Project Scientist and mission representative of ESA's Characterising Exoplanet Satellite (CHEOPS) mission a few frequently asked questions about solar systems.

What is (and isn't) a planet?

The IAU defines a true planet as a body that circles the sun without being some other object's satellite; is large enough to be rounded by its own gravity (but not so big that it begins to undergo nuclear fusion, like a star); and has "cleared its neighborhood" of most other orbiting bodies.

But that restrictive definition helped isolate what should and should not be considered a planet - a problem that arose as astronomers discovered more and more planet-like objects in the solar system. Pluto was among the bodies that didn't make the cut and was re-classified as a dwarf planet.

The problem with Pluto, aside from its small size and offbeat orbit, is that it doesn't clear its neighborhood of debris - it shares its space with lots of other objects in the Kuiper Belt. Still, the demotion of Pluto remains controversial.

The IAU planet definition also put other small, round worlds into the dwarf planet category, including the Kuiper Belt objects Eris, Haumea and Makemake.

Ceres, a round object in the Asteroid Belt between Mars and Jupiter, also got the boot. Ceres was considered a planet when it was discovered in 1801, but it was later deemed to be an asteroid. That still didn't quite fit because it was so much larger (and rounder) than the other asteroids. Astronomers instead deemed it a dwarf planet in 2006, although some astronomers like to consider Ceres as a 10th planet (not to be confused with Nibiru or Planet X).

Below is a brief overview of the eight true planets in our solar system, moving from that closest to the sun to the farthest from the sun:
Related: Solar eclipses 2023: When, where & how to see them
The sun is by far the largest object in our solar system, containing 99.8% of the solar system's mass. It sheds most of the heat and light that makes life possible on Earth and possibly elsewhere. Planets orbit the sun in oval-shaped paths called ellipses, with the sun slightly off-center of each ellipse.

NASA has a fleet of spacecraft observing the sun, such as the Parker Solar Probe, to learn more about its composition, and to make better predictions about space weather and its effect on Earth.

Mercury: The closest planet to the sun

Mercury is the closest planet to the sun and the smallest planet in the solar system - it is only a little larger than Earth's moon. Mercury zips around the sun in only 88 days and because it is so close to our star (about two-fifths the distance between Earth and the sun).

Mercury experiences dramatic changes in its day and night temperatures. Mercury temperatures can reach a scorching 840 F (450 C) in the day, which is hot enough to melt lead. Meanwhile, on the night side, temperatures drop to minus 290 F (minus 180 C).

- Diameter: 3,031 miles (4,878 km)

Mercury's atmosphere is very thin and primarily composed of oxygen, sodium, hydrogen, helium and potassium. Because the atmosphere is so thin it cannot incoming meteors, its surface is therefore pockmarked with craters, just like our moon.

Over its four-year mission, NASA's MESSENGER spacecraft revealed incredible discoveries that challenged astronomers' expectations. Among those findings was the discovery of water ice and frozen organic compounds at Mercury's north pole and that volcanism played a major role in shaping the planet's surface.

Related: How was Mercury formed?

Venus: Earth's solar system twin

Venus is the second planet from the sun and is the hottest planet in the solar system. Its thick atmosphere is extremely toxic and composed of sulfuric acid clouds, the planet is an extreme example of the greenhouse effect.

The average temperature on Venus' surface is 900 F (465 C). At 92 bar, the pressure at the surface would crush and kill you. And oddly, Venus spins slowly from east to west, the opposite direction of most of the other planets.

Venus is sometimes referred to as Earth's twin as they are similar in size and radar images beneath its atmosphere reveal numerous mountains and volcanoes. But beyond that, the planets could not be more different.

The Greeks believed Venus was two different objects - one in the morning sky and another in the evening. Because it is often brighter than any other object in the sky, Venus has generated many UFO reports.

Related: How was Venus formed?

Earth: Our home planet, filled with life

Earth, our home planet, is the third planet from the sun. It is a water world with two-thirds of the planet covered by water. Earth's atmosphere is rich in nitrogen and oxygen and it is the only world known to harbor life.

- Diameter: 7,926 miles (12,760 km)

- Orbit: 365.24 days

- Day: 23 hours, 56 minutes

- Number of moons: 1

Earth rotates on its axis at 1,532 feet per second (467 meters per second) - slightly more than 1,000 mph (1,600 kph) - at the equator. The planet zips around the sun at more than 18 miles per second (29 km per second).

Related: 10 Earth impact craters you must see

Mars: The solar system's Red Planet

Mars is the fourth planet from the sun. It is a cold, desert-like planet covered in iron oxide dust that gives the planet its signature red hue. Mars shares similarities with Earth: It is rocky, has mountains, valleys and canyons, and storm systems ranging from localized tornado-like dust devils to planet-engulfing dust storms.

Substantial scientific evidence suggests that Mars at one point billions of years ago was a much warmer, wetter world, rivers and maybe even oceans existed. Although Mars' atmosphere is too thin for liquid water to exist on the surface for any length of time, remnants of that wetter Mars still exist today. Sheets of water ice the size of California lie beneath Mars' surface, and at both poles are ice caps made in part of frozen water.

- Diameter: 4,217 miles (6,787 km)

- Number of moons: 2

Scientists also think ancient Mars would have had the conditions to support life like bacteria and other microbes. Hope that signs of this past life - and the possibility of even current lifeforms - may exist on the Red Planet has driven numerous Mars missions and the Red Planet is now one of the most explored planets in the solar system.

Related: How long does it take to get to Mars?

The asteroid belt

Between Mars and Jupiter lies the asteroid belt. Asteroids are minor planets, and according to NASA there are approximately between 1.1 and 1.9 million asteroids in the main asteroid belt larger than 0.6 miles (1 km) in diameter and millions more smaller asteroids.

The dwarf planet Ceres, about 590 miles (950 km) in diameter, resides here. A number of asteroids have orbits that take them closer into the solar system that sometimes lead them to collide with Earth or the other inner planets.

Jupiter: The largest planet in our solar system

Jupiter is the fifth planet from the sun and the largest planet in the solar system. The gas giant is more than twice as massive as all the other planets combined, according to NASA.

Its swirling clouds are colorful due to different types of trace gases including ammonia ice, ammonium hydrosulfide crystals as well as water ice and vapor.

A famous feature in its swirling clouds is Jupiter's Great Red Spot, a giant storm more than 10,000 miles wide, first observed in 1831 by amateur astronomer Samuel Heinrich Schwabe. It has raged at more than 400 mph for the last 150 years, at least.

Jupiter has a strong magnetic field, and with 75 moons, including the largest moon in the solar system, Ganymede.

Related: Jupiter's moons: Facts about the largest Jovian moons

Saturn: The ringed jewel of the solar system
Related: How far away is Saturn?
Saturn is the sixth planet from the sun and is famous for its large and distinct ring system. Though Saturn is not the only planet in the solar system with rings.

When polymath Galileo Galilei first studied Saturn in the early 1600s, he thought it was an object with three parts: a planet and two large moons on either side. Not knowing he was seeing a planet with rings, the stumped astronomer entered a small drawing - a symbol with one large circle and two smaller ones - in his notebook, as a noun in a sentence describing his discovery. More than 40 years later, Christiaan Huygens proposed that they were rings.

The rings are made of ice and rock and scientists are not yet sure how they formed. The gaseous planet is mostly hydrogen and helium and has numerous moons.

Uranus: The tilted, sideways planet in our solar system

Uranus is the seventh planet from the sun and is a bit of an oddball.

It has clouds made of hydrogen sulfide, the same chemical that makes rotten eggs smell so foul. It rotates from east to west like Venus. But unlike Venus or any other planet, its equator is nearly at right angles to its orbit - it basically orbits on its side.

- Diameter: 31,763 miles (51,120 km)

- Orbit: 84 Earth years

- Day: 18 Earth hours
Related: How did Uranus form?
- Number of moons: 27

Astronomers believe an object twice the size of Earth collided with Uranus roughly 4 billion years ago, causing Uranus to tilt. That tilt causes extreme seasons that last 20-plus years, and the sun beats down on one pole or the other for 84 Earth-years at a time.

The collision is also thought to have knocked rock and ice into Uranus' orbit. These later became some of the planet's 27 moons. Methane in Uranus' atmosphere gives the planet its blue-green tint. It also has 13 sets of faint rings.

Uranus holds the record for the coldest temperature ever measured in the solar system - minus 371.56 degrees F (minus 224.2 degrees C). The average temperature of Uranus is minus 320 degrees Fahrenheit (-195 degrees Celsius).

Neptune: A giant, stormy blue planet

Neptune is the eighth planet from the sun and is on average the coldest planet in the solar system. The average temperature of Neptune at the top of the clouds is minus 346 degrees Fahrenheit (minus 210 degrees Celsius).

Neptune is approximately the same size as Uranus and is known for its supersonic strong winds. The planet is more than 30 times as far from the sun as Earth.

Neptune was the first planet predicted to exist by using math, rather than being visually detected. Irregularities in the orbit of Uranus led French astronomer Alexis Bouvard to suggest some other planet might be exerting a gravitational tug. German astronomer Johann Galle used calculations to help find Neptune in a telescope. Neptune is about 17 times as massive as Earth and has a rocky core.

Related: There's something strange going on inside Neptune

Trans-Neptunian region

Astronomers had long suspected that a band of icy material known as the Kuiper Belt existed past the orbit of Neptune extending from about 30 to 55 times the distance of Earth to the sun, and from the last decade of the 20th century up to now, they have found more than a thousand of such objects. Scientists estimate the Kuiper Belt is likely home to hundreds of thousands of icy bodies larger than 60 miles (100 km) wide, as well as an estimated trillion or more comets.

Pluto, now considered a dwarf planet, dwells in the Kuiper Belt. It is not alone - recent additions include Makemake, Haumea and Eris. Another Kuiper Belt object dubbed Quaoar is probably massive enough to be considered a dwarf planet, but it has not been classified as such yet. Sedna, which is about three-fourths the size of Pluto, is the first dwarf planet discovered in the Oort Cloud. NASA's New Horizons mission performed history's first flyby of the Pluto system on July 14, 2015.

Pluto: Once a planet, now a dwarf planet

Pluto was once the ninth planet from the sun and is unlike any other planet in the solar system.

It is smaller than Earth's moon; its orbit is highly elliptical, falling inside Neptune's orbit at some points and far beyond it at others; and Pluto's orbit doesn't fall on the same plane as all the other planets - instead, it orbits 17.1 degrees above or below.

It is smaller than Earth's moon; its orbit is highly elliptical, falling inside Neptune's orbit at some points and far beyond it at others; and Pluto's orbit doesn't fall on the same plane as all the other planets - instead, it orbits 17.1 degrees above or below, taking 288 years to complete a single orbit according to ESA.

From 1979 until early 1999, Pluto had been the eighth planet from the sun. Then, on Feb. 11, 1999, it crossed Neptune's path and once again became the solar system's most distant planet - until it was redefined as a dwarf planet. It's a cold, rocky world with a tenuous atmosphere.

Scientists thought it might be nothing more than a hunk of rock on the outskirts of the solar system. But when NASA's New Horizons mission performed history's first flyby of the Pluto system on July 14, 2015, it transformed scientists' view of Pluto.

Pluto is a very active ice world that's covered in glaciers, mountains of ice water, icy dunes and possibly even cryovolcanoes that erupt icy lava made of water, methane or ammonia.

Related: Why isn't Pluto a planet anymore?

Planet Nine: A planet search at solar system's edge

In 2016, researchers proposed the possible existence of a ninth planet, for now, dubbed "Planet Nine" or Planet X. The planet is estimated to be about 10 times the mass of Earth and to orbit the sun between 300 and 1,000 times farther than the orbit of the Earth.

Scientists have not seen Planet Nine. They inferred its existence by its gravitational effects on other objects in the Kuiper Belt, a region at the fringe of the solar system that is home to icy rocks left over from the birth of the solar system. Also called trans-Neptunian objects, these Kuiper Belt objects have highly elliptical or oval orbits that align in the same direction.

Scientists Mike Brown and Konstantin Batygin at the California Institute of Technology in Pasadena described the evidence for Planet Nine in a study published in the Astronomical Journal. The research is based on mathematical models and computer simulations using observations of six other smaller Kuiper Belt Objects with orbits that aligned in a similar matter.

A hypothesis proposed in September 2019 on the pre-print server arXiv suggests Planet Nine might not be a planet at all. Instead, Jaku Scholtz of Durham University and James Unwin of the University of Illinois at Chicago speculate it could be a primordial black hole that formed soon after the Big Bang and that our solar system later captured, according to Newsweek. Unlike black holes that form from the collapse of giant stars, primordial black holes are thought to have formed from gravitational perturbations less than a second after the Big Bang, and this one would be so small (5 centimeters in diameter) that it would be challenging to detect.

Astronomers continue to come up empty in their search for Planet 9. A recent 2022 sky survey using the 6-meter Atacama Cosmology Telescope (ACT) in Chile found thousands of tentative candidate sources but none could be confirmed.

Related: The nonexistent planet Nibiru

The edge of the solar system

Past the Kuiper Belt is the very edge of the solar system, the heliosphere, a vast, teardrop-shaped region of space containing electrically charged particles given off by the sun. Many astronomers think that the limit of the heliosphere, known as the heliopause, is about 9 billion miles (15 billion km) from the sun.

The Oort Cloud lies well past the Kuiper Belt, considered to be located between 2,000 and 5,000 astronomical units (AU) from the sun. The outer edge of the Oort Cloud may reach as far as 10,000 up to 100,000 AU from the sun. One AU is equal to approximately 93,000,000 miles (150 million kilometers). The Oort Cloud is home to billions, or even trillions of objects, according to NASA Science.

Solar system formation and discovery

Approximately 4.5 billion years ago a dark cloud of gas and dust began to collapse. As it shrank, the cloud flattened into a swirling disk known as a solar nebula, according to NASA Science.

The heat and pressure eventually became so high that hydrogen atoms began to combine to form helium. The nuclear reactions released vast amounts of energy and our sun was formed.

The sun accumulated about 99% of the available matter and the remaining material further from the sun formed smaller clumps inside the spinning disk. Some of these clumps gained enough mass that their gravity shaped them into spheres, becoming planets, dwarf planets and moons. Other leftover pieces became asteroids, comets and smaller moons that make up our solar system.

Read more: How did the solar system form?

For millennia, astronomers have followed points of light that seemed to move among the stars. The ancient Greeks named them planets, meaning "wanderers." Mercury, Venus, Mars, Jupiter and Saturn were known in antiquity, and the invention of the telescope added the Asteroid Belt, Uranus, Neptune, Pluto and many of these worlds' moons. The dawn of the space age saw dozens of probes launched to explore our system, an adventure that continues today.
NASA solar system exploration
There have been five human-made objects so far, Voyager 1, Voyager 2, New Horizons, Pioneer 10 and Pioneer 11, that have crossed the threshold into interstellar space.

Related: How much of the solar system is made of interstellar stuff?

Additional resources

Explore the solar system in greater detail with these interactive resources from NASA. Discover the wonders of the solar system with this educational material from ESA. See where the planets are in their current orbit of the sun with this interactive orrery from NASA.

Bibliography

Prialnik, Dina K., Antonella Barucci, and Leslie Young, eds. The Trans-Neptunian Solar System. Elsevier, 2019.

Pirani, Simona, et al. " Consequences of planetary migration on the minor bodies of the early solar system." Astronomy & Astrophysics 623 (2019): A169.

Scholtz, Jakub, and James Unwin. " What if Planet 9 is a primordial black hole?." Physical Review Letters 125.5 (2020): 051103.

Brown, Michael E., and Konstantin Batygin. " Observational constraints on the orbit and location of planet nine in the outer solar system." The Astrophysical Journal Letters 824.2 (2016): L23.

Raymond, Sean N., et al. " Building the terrestrial planets: Constrained accretion in the inner Solar System." Icarus 203.2 (2009): 644-662.

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Solar System Planets: Order of the 8 (or 9) Planets

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Explore the eight (or nine) planets of the solar system in order from nearest to the sun and discover the many wonders of our solar system along the way.

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For Māori Language Week we're looking at the names of the main objects in te whānau a Tamanuiterā (the Solar System).

This is a bit tricky because different iwi have different names for celestial objects, complicated further by some disagreement over the "correct" names. In consultation with various tohunga over the years I've developed a list of common names which I'll share below, starting at the centre of te whānau a Tamanuiterā and working outwards. This is not an exhaustive list - just the names I hear most often.

The Sun's personified name is Tama-nui-te-rā but as an astronomical object it is usually just called te rā.

Mercury is Takero, Apārangi, or Whiro.

Venus has different names depending on whether it appears in the evening or morning. It can be Kōpū (evening or morning), Tāwera (evening but more commonly morning), or Meremere-tū-ahiahi (evening).

Earth has the personal name Papatūānuku but as a globe it is referred to as te ao.

The Moon is usually Marama but is sometimes called Rona.

Mars is usually Matawhero, sometimes Tūmataueka.

Jupiter can be Pareārau, Kōpūnui, or Rangawhenua.

Saturn is Pareārau in some dialects, leading to some confusion between it and Jupiter. More commonly it's called Rongo, occasionaly Roko.

The last two planets are not generally visible with the naked eye and were discovered after the invention of telescopes. Therefore they weren't known to traditional Māori astronomers (tohunga kōkōrangi) and their names are modern additions to te reo Māori.

Uranus is Rakipō, Whērangi, or Rangipō.

Neptune is Tangaroa or Takaroa.

If you're interested in learning more about tātai arorangi (Māori astronomy), there are a number of websites and a few books that cover the topic. However you do need to be aware that there are some questionable resources out there. Be careful and pay attention to the sources behind the material.

My preferred authority is Dr Rangi Matamua of the University of Waikato, one of the founders of the Society of Maori Astronomy Research and Traditions ( www.maoriastronomy.co.nz). Anything with his name on it can be trusted.
Below: This column as it appeared in the Wāipa Post

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Your Night Sky - September 2018 - Māori Planet Names

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For Māori Language Week we're looking at the names of the main objects in te whānau a Tamanuiterā (the Solar System). This is a bit tricky because different iwi have different names for celestial objects, complicated further by some disagreement over the "correct" names.

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Revolutionary ideas about our Solar System

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Revolutionary ideas about our Solar System

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Since the earliest times, humans have made observations of the night sky. These observations, particularly of the Earth, Moon, Sun and planets (visible to the naked eye), led to the development of models to explain the movement of these natural satellites as seen in the night sky.

With the development of the telescope, more accurate measurements of night sky objects were possible. This, along with the development of a more 'scientific' interpretation of the collected evidence, caused a major shift from an Earth-centred view (geocentric) of the Universe to a Sun-centred one (heliocentric).

Ptolemaic model

In the second century CE, Ptolemy, who lived in the Egyptian town of Alexandria, produced a mathematical representation based on observation of the known Solar System. In Ptolemy's model, the Earth was at the centre of the Universe, with the Sun and planets revolving in a series of circular orbits moving out from the Earth. This model became known as the 'geocentric' model.

Copernican model

Nicolas Copernicus (1473-1543) was a Polish scholar who reconstructed Ptolemy's model of the Universe. Over the 1200 years since Ptolemy's model was put forward, it had been developed into a complex and cumbersome mathematical system. Copernicus was able to simplify it by switching from an Earth-centred model to a Sun-centred one.

The Roman Catholic Church, whose teachings held firmly to the Ptolemaic model, rejected his 'heliocentric' ideas. Copernicus's work was banned and remained out of favour until 1822.

Tycho Brahe

The Dane Tycho Brahe (1546-1601) was born 3 years after the death of Copernicus. He studied mathematics and astronomy in German and Swiss universities and came to the conclusion that the Copernican model defied God's word as written in the scriptures. He proposed a model with the Sun revolving around the Earth and the planets orbiting the Sun.

Tycho Brahe observed the motions of stars and planets and recorded their movements. He had an island observatory equipped with the best available instruments of the time (minus the telescope since it had not been invented). Years of careful observation allowed him to catalogue, with an exceptionally high degree of accuracy, the positions of stars and the movement of the visible planets. In 1572, he observed the appearance of a very bright new star. This was controversial because the belief of the time was that the stars were fixed. Tycho had observed a supernova, now named SN 1572.

Kepler - laws of planetary motion

Shortly before his death, Tycho Brahe appointed as his assistant a young German, Johann Kepler (1571-1630). Kepler took over Brahe's records and edited and extended them with his own observations. Kepler, who was a follower of the Copernican model, realised the orbits of the planets could be elliptical rather than circular.

Using Brahe's data on the movement of Mars, Kepler developed his laws of planetary motion.

The orbit of every planet is an ellipse with the Sun at one of the two foci.

A line joining a planet and the Sun sweeps out equal areas during equal intervals of time.

The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit.

These laws added considerable weight to the acceptance of the heliocentric model of the Universe.

Galileo discovers Jupiter's moons

Galileo (1564-1642) lived at the same time as Kepler but they were not in regular communication. Using the newly discovered telescope, Galileo discovered that Jupiter had four moons. At first, he thought they were stars, but he noticed that, each night, the four points of light appeared to change positions slightly.

Galileo's discovery of four of Jupiter's moons was evidence that objects can orbit around other objects. He argued that if moons orbit around other planets, then perhaps the Earth is not the centre of all motion of the stars and planets. Galileo stated that the Earth and the planets must all orbit around the Sun (heliocentric).

1500 years ago, everybody knew the Earth was the centre of the Universe. 500 years ago, everybody knew the Earth was flat... Imagine what you'll know tomorrow.
Agent K (Tommy Lee Jones) in the movie Men in Black

Nature of science

Newton and gravity

Sir Isaac (1642-1727) was born in the same year that Galileo died. His studies of the motion of objects on Earth and of natural satellites in the night sky resulted in three laws of motion and a law of universal gravitation. He linked universal gravitation to Kepler's laws of planetary motion. This monumental discovery meant that the heliocentric model of the Solar System was finally accepted by the scientific community

The journey from the geocentric to the heliocentric model was a long and tortuous one. It was the collection of empirical evidence along with mathematical applications in conjunction with insightful deep-thinking minds that finally replaced the geocentric model with the heliocentric one.

Useful links

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Since the earliest times, humans have made observations of the night sky. These observations, particularly of the Earth, Moon, Sun and planets (visible to the naked eye), led to the development of models to explain the movement of these natural satellites as seen in the night sky.

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What's that? Right there! Way up in the ...is it a bird? Could it be a plane? Maybe it's an elephant! Or a badger? Or a giant panda bear driving a car!

When you look up high in the sky and see those white, wispy forms floating through the , you notice that they can look like all sorts of things. What are we talking about? Clouds, of course!

Have you ever stopped to WONDER exactly what clouds are? How do they get there? Are they made of smoke that floats up high into the atmosphere ? Could they be placed there by magical creatures who like to paint the sky?

Don't get too excited about the thought of magical creatures painting pictures in the sky for you. When it comes to clouds, they can be explained easily by science!

The is also full of other particles, including , dirt, and salt. Scientists call these particles aerosols. People who study the , called meteorologists, also call these particles condensation or seeds.

Clouds form when droplets of condense from a gas back into a liquid. This process, called condensation , occurs when the becomes , which means it cannot hold any more .

Other factors, such as fronts of warm and cold colliding, the movement of the jet stream, and variances in winds, can also affect formation. Topographical features of Earth's surface, such as mountain ranges, can also influence the flow of and thus the creation of clouds.

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What's that? Right there! Way up in the ...is it a bird? Could it be a plane? Maybe it's an elephant! Or a badger? Or a giant panda bear driving a car! When you look up high in the sky and see those white, wispy forms floating through the , you notice that they can look like all sorts of things.

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Earth's Atmosphere: StudyJams! Science | Scholastic.com

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The atmosphere is composed of a mixture of gases that blanket the Earth. This activity will teach students about the different layers of Earth's atmosphere.

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Earth’s atmosphere is a jacket of gases that surrounds our planet. It keeps us warm, gives us oxygen to breathe, and it is where our weather happens.

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See Mr Wells for the template

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Describe aspects of geology, understand that rocks (along with water, air and soil) make up our planet and recognise that these are our resources

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Describe aspects of geology, understand that rocks (along with water, air and soil) make up our planet and recognise that these are our resources

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What rocks do we mine? Why?

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Follow the history of gold coal and ironsand mining, and finding pounamu, Examine the conservation and environmental issues around mining. Also covered are types of mining, technology, mining dangers wealth, benefits, and disasters. SCIS no. 1865227

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Follow the history of gold coal and ironsand mining, and finding pounamu, Examine the conservation and environmental issues around mining. Also covered are types of mining, technology, mining dangers wealth, benefits, and disasters. SCIS no. 1865227

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In this activity, students use app and web-based resources to help them spot and learn more about artificial satellites as they move across the sky.

By the end of this activity, students should be able to:

use selected internet resources to further their knowledge about satellites and their orbits

use some of the terminology associated with satellite spotting

discuss why we can see some satellites more easily than others.

Download the Word file (see link below) for:

introduction/background notes

what you need

what to do

student handout.

Useful links

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In this activity, students use app and web-based resources to help them spot and learn more about artificial satellites as they move across the sky. By the end of this activity, students should be able to: use selected internet resources to further their knowledge about satellites and their orbits use some of the terminology associated with satellite spotting discuss why we can see some satellites more easily than others.

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A satellite is anything that orbits around another object. Moons are natural satellites that around planets, whereas artificial satellites are objects that people have made and launched into orbit using rockets.

There are over a thousand active satellites orbiting the Earth with a range of functions. We are becoming increasingly dependent upon them, especially in the areas of weather monitoring, navigation assistance, communications, Earth and space observation and national security.

The science ideas that allow satellites to remain in orbit are principally ones of gravitational forces and circular motion.

Gravity and satellite motion

Gravity is a force that attracts all objects towards each other. It is gravity that keeps the Earth's natural satellite, the Moon, and its largest artificial satellite, the International Space Station (ISS), in orbit around the Earth. However, both these satellites have sideways motion in the form of orbital speed that keeps them from falling back to Earth. Find out more in the article Gravity and satellite motion.

Natural satellites

Moons are natural satellites that orbit around planets. Other space objects such as planets, asteroids and comets can be regarded as satellites.

The Galilean moons of Jupiter can be viewed with the aid of binoculars or a simple telescope, and the timing of the Moon's passage around the Earth has led to the definition of two types of month - sidereal and synodic.

Artificial satellites

There are currently over a thousand active artificial satellites orbiting the Earth. The size, altitude and design of a satellite depend on its purpose. Although communication, weather, navigation and observation satellites come in a wide range of sizes, they do have common basic parts such as a power source, propulsion system, computer system and communication system. Learn about how satellites are launched into space and how some of them have become space junk.

Communications satellites

Communications satellites are used to send and receive radio signals for television, phone or internet communications. Large concave reflectors called satellite dishes are normally used to send and receive these signals. Without these satellites, the connectivity of the 'global village' would collapse.

Revolutionary ideas

Since the earliest times, humans have made observations of the night sky. These observations, particularly of the Earth, Moon, Sun and planets (visible to the naked eye), led to the development of models to explain the movement of these natural satellites as seen in the night sky. Over time, there was a move from the geocentric model to the heliocentric model. Find out more in the article Our solar system - revolutionary ideas and the timeline History of satellites.

Meet the scientists

Dr Allan McInnes is a senior lecturer in the Electrical and Computer Engineering Department of the University of Canterbury. His extensive experience in the satellite industry along with his excellent communication skills feature in several of the video clips.

Dr Wolfgang Rack is a senior lecturer in the Gateway Antarctica programme at the University of Canterbury. One of his research projects involves measuring sea-ice thickness in Antarctica using the CryoSat-2 satellite

Dr Adrian McDonald is a senior lecturer in the Physics and Astronomy Department of the University of Canterbury. His ozone depletion work and Antarctic climate measurement research take him to Antarctica for 2-3 weeks each year.

Kelvin Barnsdale is senior research engineer in the College of Engineering at the University of Canterbury. His expertise in radio frequencies and electronics led to work on Space Shuttle missions and designing GPS systems.

Warwick Holmes is an avionics systems engineer who helped to build, test and launch the Rosetta spacecraft.

Take up the challenge

Student activities include a mix of hands-on and literacy-based investigations. Consider beginning a teaching sequence with Gravity and satellites - true or false? The activity is supported by the teacher resource Alternative conceptions about gravity and is a useful pretest to establish student understanding.

Students turn their eyes to the night sky to observe natural satellites and to spot artificial satellites - like the ISS - as they pass overhead. Back indoors, students can hunt for satellites online with a webquest.

Two activities use models to teach science concepts. Scale model for satellite orbits explores satellite altitudes and satellite motion. Investigating satellite dishes uses an umbrella as a curved reflector to increase a cellphone's Wi-Fi signal.

Question bank

The Investigating satellites - question bank provides an initial list of questions satellites and places where their answers can be found. The questions support an inquiry approach.

Key terms

For explanations of key concepts, see Investigating satellites - key terms.

Timeline

Explore the timeline to see key dates relating to early discoveries about natural and artificial satellites in this timeline.

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A satellite is anything that orbits around another object. Moons are natural satellites that around planets, whereas artificial satellites are objects that people have made and launched into orbit using rockets. There are over a thousand active satellites orbiting the Earth with a range of functions.

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We live in a very exciting country. A day's drive in a car can take us from snowy mountains, past geysers and hot mud pools to white, sandy Pacific beaches. Have you ever wondered why New Zealand has so many different types of landscapes? Our extremes are due to where our country sits. The good news is that we get to enjoy rugged mountains for skiing and tramping and thermal spots for warm swims. The not so good news is that we also get shaky ground in the form of earthquakes and, less often, volcanic eruptions.

New Zealand sits on the edges of two tectonic plates - the Australian and the Pacific plates. The plates slowly move and push against each other. This has created our mountains and our many extinct and active volcanoes. The plates are also responsible for the thousands of earthquakes we have every year.

What is an earthquake?

Very simply, an earthquake is a release of energy. If you brace your shoulder against someone else's shoulder and push, the energy is stored up until one of you is pushed aside. The same thing happens with the tectonic plates. They push or scrape against each other until something has to give - and boom! The energy is released. The energy spreads outward in waves, which shake the Earth. The ground starts to shake once the waves reach the Earth's surface. New Zealand records 14,000-15,000 earthquakes every year. Around 100 to 150 are big enough for us to feel.

What is a volcano?

We usually think of volcanoes as cones with smoke coming from the top - and it's true for some volcanoes like Mt Ruapehu. But scientists say a volcano is an opening in the Earth's crust in which lava, steam, gases or ash is ejected. Some volcanoes are actually deep craters called calderas. New Zealand has had some amazing volcanic eruptions in its history, but most of our volcanoes are dormant (asleep) or extinct. White Island is our most continually active volcano. It's been active for 150,000 years! Fortunately, it mostly releases gases and steam.

Are volcanoes and earthquakes related?

Volcanoes and earthquakes are often found in the same place, but are they related? Does one trigger the other? In New Zealand, volcanoes and earthquakes are related in that they are both caused by the tectonic plates our country sits on. Sometimes the pressure of magma forcing its way through to the Earth's surface will trigger earthquake activity. For example, when Tarawera erupted in 1886, more than 30 earthquakes were felt in the Rotorua region just before the eruption.

Monitoring earthquakes and volcanoes

GNS Science is the Crown research institute responsible for monitoring earthquakes and volcanoes. Their GeoNet Project uses special equipment to observe and monitor the land. GNS scientists gather this information to learn about our shaky country so they can warn us and try and reduce the risk of harm.

Nature of Science

Useful links

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We live in a very exciting country. A day's drive in a car can take us from snowy mountains, past geysers and hot mud pools to white, sandy Pacific beaches. Have you ever wondered why New Zealand has so many different types of landscapes? Our extremes are due to where our country sits.

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Plate tectonics, Volcanoes and Earthquakes

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Plate tectonics, Volcanoes and Earthquakes

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The Earth rumbles and a hiss of steam issues from the top of Mt Ruapehu. Are these two events related? Is the earthquake caused by the volcano? Or is the steam caused by the earthquake?

Tectonic plates

When Alfred Wegener first proposed the idea of continental drift (the precursor idea to plate tectonic theory), it didn't quite explain the full story. While he correctly showed that Africa and South America fitted together, his model wasn't able to explain the violent forces that occur around the Earth's crust.

It wasn't until the 1960s that a full explanation began to develop - the theory of plate tectonics. This theory explained many pieces of the puzzle that scientists had observed, for example, continental fit, matching geology, past glaciation, movements of the ocean floor and the location of fossils of ancient animals and plants.

Scientists now believe that the crust of the Earth consists of rigid interconnecting plates (6 major plates and a few smaller ones). Plates are thought to float on the partially molten mantle, moving away from oceanic ridges where new plate material is produced and moving past each other or colliding along plate boundaries. Earthquakes and volcanoes are related to this movement.

Explore plate tectonics further.

Colliding plates

Where plates come into contact, energy is released. Plates sliding past each other cause friction and heat. Subducting plates melt into the mantle, and diverging plates create new crust material.

Subducting plates, where one tectonic plate is being driven under another, are associated with volcanoes and earthquakes. This activity is focused along the edge of the plate boundary where two plates come into contact, forming regions such as the Pacific Ring of Fire - a chain of earthquake and volcanic activity around the edge of the Pacific Ocean - which generates 75% of the world's volcanoes and 80% of the world's earthquakes.

Diverging plates

When plates move away from each other, the space between them gets filled with material, which rises to the surface, cools and forms mid-oceanic ridges. The Pacific Ocean is growing wider by about 18 cm per year as the plates diverge and the mid-oceanic ridge is built up.

Subducting plates and volcanoes

Plate material that is produced along the ocean floor is generally quite dense and relatively heavy. Continental plates don't tend to get subducted. When oceanic plate is pushed from the mid-ocean ridge towards a plate boundary with a continental plate, it tends to subduct or dive below the continental crust. In this process, water is also being subducted with the oceanic plate. Friction increases the heat along such boundaries, which causes this material to melt and mix the oceanic plate material, the continental plate material and the water.

Andesite volcanoes tend to form at these subduction boundaries. This may have something to do with differences in plate densities and the release of gases, such as water vapour. As more heat is being produced through the subduction process, the mix of more and less volatile ingredients causes changes in density and pressure, which are linked to volcanic activity.

Volcanoes and earthquakes

Volcanoes and earthquakes are often found in the same place, but are they related? Does one trigger the other? The answer seems to be yes - but not always. They are sometimes linked but are often independent events.

When a volcano erupts, the pressure of the rising magma forcing its way through the crust to the surface will often trigger earthquake activity. Scientists have been able to demonstrate this link and also know what type of earthquake to look for.

Conversely, an earthquake may trigger subsequent eruptions. As the crust changes and moves in a major earthquake, fissures or cracks can form that may act as pipelines for magma and future volcanoes. This is harder to monitor and test and is an area of active research.

Related content

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Plate tectonics, volcanoes and earthquakes

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The Earth rumbles and a hiss of steam issues from the top of Mt Ruapehu. Are these two events related? Is the earthquake caused by the volcano? Or is the steam caused by the earthquake? When Alfred Wegener first proposed the idea of continental drift (the precursor idea to plate tectonic theory), it didn't quite explain the full story.

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Earthquakes are a fact of life in New Zealand, but we still don't understand exactly what triggers them. Microscopes are some of the many tools that scientists are using to get a better understanding of what happens in an earthquake.

Professor Dave Prior and his team at the University of Otago are looking at 'squished' rocks from deep in the Alpine Fault (an active fault on the west coast of the South Island). They use microscopes of several kinds to study the features of each rock and work out its life story - the things that have happened to it over time. By doing this, they hope to build up a picture of the forces at work deep within the Alpine Fault.

Hard as rock?

We tend to think of rocks as being very hard objects that shatter when they're placed under stress (such as during an earthquake). Rocks do shatter at the Earth's surface, but deeper underground, they get squished under pressure instead of breaking. This is because they are quite cold and brittle at the surface, but hotter and softer underground. Dave describes rocks as being like chocolate - on a cold day, your chocolate bar will break in two when it's forced, but on a warmer day, it'll bend without breaking.

Many geologists believe that movement of rock within the 'squishing zone' plays a big role in triggering earthquakes. No one knows, though, exactly how the squishing and earthquakes are linked. Dave thinks the Alpine Fault might hold the answers - he says it's the best place in the world to study squishy deformation of rocks in a fault zone.

The Alpine Fault: bringing up rocks from the deep

The Alpine Fault is special because it has a reverse fault motion, as well as moving in other ways, which means that one side of the fault is being raised up with respect to the other. Rocks that were once deep underground are brought to the surface by the action of the fault. They can be studied to give information about what happened deep within the fault in the distant past.

There are other big reverse faults in the world, but the Alpine Fault is unusual because it has been moving in the same way for approximately the last 5 million years. As Dave puts it, "It's probably the only major fault in the world where you can see at the surface the squished rocks that were formed less than a million years ago at 10-20 km depth."

We're using the Earth as a laboratory to create material that tells us about how rocks move around and change shape.
Professor Dave Prior, Department of Geology, University of Otago

Reading the rocks with microscopes

By observing rocks from the Alpine Fault under the microscope, Dave and his colleagues have learnt a lot about conditions deep in the fault. They focus on two techniques:

Polarising optical microscopy: The optical microscopes used by geologists have a polarising filter so that different minerals show up as different colours under polarised light. Dave and his team use the polarising optical microscope to see which minerals are in the squished rocks and to learn about their shapes, sizes and orientations.

Electron backscatter diffraction When rocks get squished within the fault zone, the crystals within them tend to line up in preferred directions. The direction of the crystals depends on the direction the rock was squished in. Electron backscatter diffraction, which is done using a scanning electron microscope (SEM), measures the orientation of the crystals (lattice planes) in very small volumes of the rock. This means Dave's team can tell the direction in which the rock was squished and the conditions (the temperature, for example) deep in the fault zone at the time.

Drilling into the fault

Dave and his colleagues are part of the Deep Fault Drilling Project - a multinational collaboration that aims to drill down several kilometres in the Alpine Fault zone. Rock cores will be collected through the depth of the drilling holes, and Dave and his team will study these using microscopy in the same way they study their samples from the surface. The drilling project won't go as deep as the squishing zone, but it will allow the team to study rocks from shallower parts of the fault where earthquakes are generated.

Nature of science

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Earthquakes are a fact of life in New Zealand, but we still don't understand exactly what triggers them. Microscopes are some of the many tools that scientists are using to get a better understanding of what happens in an earthquake.

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Compare and contrast Tsunamis and Surf Waves

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Compare and contrast Tsunamis and Surf Waves

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In this activity, students use an interactive or paper-based Venn diagram to illustrate the key similarities and differences between tsunami waves and surf waves.

By the end of this activity, students should be able to:

describe the key similarities and differences between tsunami waves and surf waves

understand how to use a Venn diagram to graphically organise information.

Download the Word file for:

introduction/background notes

what you need

what to do

discussion questions

extension ideas

student worksheets.

Useful link

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Similarities and differences: tsunamis and surf waves

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In this activity, students use an interactive or paper-based Venn diagram to illustrate the key similarities and differences between tsunami waves and surf waves. By the end of this activity, students should be able to: describe the key similarities and differences between tsunami waves and surf waves understand how to use a Venn diagram to graphically organise information.

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If you've ever taken a bath or swum in a lake or pool, you've probably enjoyed creating your own waves. Unlike solid objects, water is and easy to move around. The harder you push with your hands, the bigger the waves will be.

Now imagine what happens in the ocean when an earthquake occurs underground. If you've ever felt an earthquake or seen one on television, you know that they have the power to shake the ground and move large buildings.

When an earthquake occurs under the ocean floor, the earthquake 's massive energy is transferred to the water above it, creating a series of water waves called a . The word comes from the Japanese words tsu (harbor) and nami (wave).

In addition to earthquakes, tsunamis can be caused by other events that generate enough energy to displace a large volume of water, such as eruptions, landslides, meteors, and even underwater tests of devices. Given the frequent earthquake and activity in the Pacific Rim, tsunamis happen often in Japan.

Tragically, because of the huge amounts of water and energy involved, tsunamis can cause tremendous damage to coastal areas. On December 26, 2004, a massive earthquake in the Indian Ocean caused a series of devastating tsunamis along the coasts of the areas bordering the Indian Ocean. One of the deadliest natural disasters in history, waves up to 100 feet high crashed into coastal communities, killing over 230,000 people in 14 countries, including Indonesia, Sri Lanka, India, and Thailand.

You may recall the earthquake and that occurred in Japan on March 11, 2011. That resulted in mass destruction including a power plant that released into the Pacific Ocean.

Normal ocean waves created by the wind have an average wavelength (measured from crest to crest) of approximately 330 feet and an average height of about 6.6 feet. A , on the other hand, can have a wavelength of 120 miles or more. Traveling at up to 500 miles per hour in the deep ocean, a 's height might only be as little as 3 feet, making it almost impossible to detect, even for a ship in the area.

As a approaches a , though, things begin to change dramatically. As it approaches shallow waters, an effect known as wave shoaling compresses and slows the wave to below 50 miles per hour. Wavelength also decreases dramatically, but - the height of the wave - increases greatly, leading to the unmistakable wall of water that causes such destruction along coastlines.

Approximately 80% of tsunamis happen in the Pacific Ocean, although they're possible in any large body of water, including lakes. Tsunamis cannot be prevented and can rarely be predicted with . In the event of an earthquake , oceanographers, geologists, and seismologists often urge potentially-affected areas to issue warnings.

Regions that experience tsunamis regularly have developed warning systems to give as much advance warning as possible to people who live along the . In Japan, for example, coastal communities are well-educated about earthquakes and tsunamis. Japanese shorelines feature warning signs and warning sirens atop nearby hills.

Although tsunamis cannot be prevented, some - countries use engineering lessons learned from earthquakes to reduce shoreline damage. Many Japanese coastal communities have built walls, floodgates, and channels to block or redirect water from incoming tsunamis.

One of the best ways to make a coast -proof, though, is quite natural: plant trees! Scientists noticed that some locations in the path of the 2004 Indian Ocean suffered little damage because trees, such as coconut palms and mangroves, absorbed the 's energy. In fact, one small Indian village saw little damage because the broke against a forest of over 80,000 trees that had been planted along the shoreline just two years earlier in an attempt to set a Guinness World Record.

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Surfers beware! Today's Wonder of the Day features a wave that you won't want to catch. Find out what happens when the Earth quakes and the oceans roar...

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What is it like to live on a Space Station?

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What is it like to live on a Space Station?

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Have you ever dreamed of being an astronaut? How about stepping foot on another planet? Would you like to live on a spacecraft orbiting high above Earth? What would it be like to live on the International Space Station?

It's probably similar to life on the U.S.S. Enterprise from Star Trek, right? Or would it be more like staying at a posh resort? Maybe it's sort of like living in your car?

The future predicted by Star Trek hasn't quite come along yet. The International Space Station (ISS) is a bit different from either a posh resort or your average automobile. So what's life aboard the ISS like?

The ISS is a that Earth once every 90 minutes at an altitude of over 220 miles. The space agencies of the United States, Russia, Japan, Canada, and several European countries work together to keep it running.

The ISS can house up to 10 astronauts. Their expeditions can last up to six months at a time. During that time, astronauts aboard the ISS follow a detailed daily schedule. It tells them when to get up, eat, exercise, work, relax, and go to sleep.

The ISS has over 15,000 cubic feet of living space. It includes more room than your average three-bedroom home. Its laboratory is a key feature that makes all sorts of interesting possible. In the lab, gravity can be virtually eliminated for extended periods of time.

The microgravity environment of the ISS makes everyday activities, such as washing your hair and going to the bathroom, a bit more challenging than on Earth. Astronauts wash their hair with a rinseless shampoo. To use the bathroom, they must strap themselves to the toilet with leg restraints and thigh bars. The toilet itself acts like a vacuum cleaner that sucks air and waste into special tanks.

Astronauts must spend about two hours each day exercising. They use special equipment built just for the ISS. Without regular exercise, astronauts would lose a lot of muscle and bone. This is due to the low gravity of space.

The food astronauts eat is designed for space missions. It comes in disposable packages that can be stored easily. Some foods, such as brownies, can be eaten in space just like they are on Earth. Others pose special challenges. Do you like salt on your food? When you're in space, you can't shake salt onto food, because it would simply float away! As a result, astronauts have to use a special liquid version of salt.

When they're not busy with scientific experiments or maintenance on the ISS, astronauts can relax and have fun in a variety of ways. Sometimes it's fun to simply stare out the window at Earth spinning below. Other activities include listening to music, reading books, playing cards, watching movies, and talking with their families.

As you can see, living on the ISS presents certain challenges that don't exist on Earth. What do you think? Would you enjoy spending six months or more on the ISS?

NGSS.ESS1.B, CCRA.L.3, CCRA.L.6, CCRA.R.1, CCRA.R.2, CCRA.R.4, CCRA.R.10, CCRA.SL.1, CCRA.SL.2, CCRA.W.3, CCRA.L.1, CCRA.L.2

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What Is It Like To Live on the International Space Station?

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Have you ever dreamed of being an astronaut? How about stepping foot on another planet? Would you like to live on a spacecraft orbiting high above Earth? What would it be like to live on the International Space Station? It's probably similar to life on the U.S.S. Enterprise from Star Trek, right?

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How did astronauts build a space station?

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How did astronauts build a space station?

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What's that up there? Right there! Way up high in the sky, there's a bright dot moving slowly across the black canvas of the heavens. It's way too high to be an airplane, and it's too steady to be a shooting star. What could it be? It's the International Space Station, of course!

Visible from Earth with the naked eye, the International Space Station (ISS) is a satellite. It serves as a microgravity laboratory in space. At costs approaching $150 billion, the ISS is arguably the most expensive thing ever built. It's also the largest structure ever built in space by humans.

On the ISS, a of international astronauts conducts science experiments. These cover a wide range of disciplines, from astronomy and biology to geology and physics. The ISS completes 15.5 orbits around Earth each day. That means astronauts enjoy a sunrise or sunset about every 92 minutes.

How can the ISS orbit Earth so quickly? Orbiting at an average altitude of 248 miles above Earth, the ISS travels approximately 17,500 miles per hour. That's a rate of about five miles per second! Each day, the ISS travels a distance nearly equal to traveling from Earth to the Moon and back.

Despite its speed, the ISS is visible from Earth with the naked eye. You just need to know when and where to look. That's because the ISS is so big. How big? The ISS consists of and connecting that house living quarters and laboratories. It also has large for support, as well as more than an acre of solar panels that provide power.

In total, the ISS is a little bigger than an American football field. It weighs approximately 900,000 pounds. Inside, there are two bathrooms, a gymnasium, and the living space of about a six-bedroom house.

So how did such a humongous man-made object get into space? It would be impossible to launch such a huge object with modern technology. That's why the ISS was built slowly, piece-by-piece. Five different space agencies representing 15 different countries worked on the project.

The first piece, Russia's Zarya module, was launched into space in 1998. Over time, other were launched via rockets and the United States space shuttle program. Astronauts connected all the pieces over the course of several missions. The ISS has been continuously occupied since November 2000.

Since that time, more than 200 astronauts from 15 different countries have visited the ISS. Space agencies hope to continue to use the ISS for many years to come. In fact, there are current plans to add even more in the coming years.

Have you ever spotted the ISS in the night sky? Would you like to live aboard this space station one day? Anything is possible! As astronauts add to the ISS, it could grow to hold even more experts from all over the world.

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How Did Astronauts Build a Space Station?

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Today's Wonder of the Day is out of this world!

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10...9...8...7...6...5...4...3...2...1...blast off! Today Wonderopolis is leaving Earth and heading for space.

Growing up in today's world, it can be hard to imagine a time when outer space was a true mystery. You already know men have walked on the Moon. The International Space Station orbits Earth and sends back all sorts of information.

The Hubble telescope travels throughout the solar system, sending amazing pictures back to Earth. The Mars Rover is exploring the surface of Mars and helping scientists learn new things every day.

Way back in the day, though, outer space was an unexplored . The people of Earth could only look up at the sky and WONDER about what was up there.

All that changed on April 12, 1961. That day, Russian Yuri Gagarin became the first human being in space. In the Russian Vostok 1 spacecraft, he made his historic 108-minute around Earth - a place no man had gone before.

Gagarin's accomplishment set off a competition between the United States and the Soviet Union known as the "space race." The countries sought to outdo each other to accomplish newer and more daring in space. For example, Alan Shepard became the first American in space less than a month after Gagarin.

An even greater was reached a few years later. On July 21, 1969, American Neil Armstrong became the first man to walk on the Moon as part of the mission. Upon stepping onto the surface of the Moon, Armstrong spoke these famous words: "That's one small step for man, one giant leap for mankind."

Gagarin and Armstrong's groundbreaking space travels paved the way for what was to come. From space shuttle flights to manned space stations orbiting the Earth, we now know much more about the world beyond Earth's atmosphere than would've ever been possible without these pioneers!

Today, scientists tend to use modern technology in the form of unmanned space rovers and larger and larger telescopes to explore the outer reaches of space. Manned missions are becoming more and more scarce. Would you like to be on the cutting edge of future astronomical discoveries? If so, you might want to pursue a career in a field such as science, technology, engineering or mathematics. You never know when your name might be attached to the next spacecraft that explores beyond Mars into the outer reaches of our solar system!

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10...9...8...7...6...5...4...3...2...1...blast off! Today Wonderopolis is leaving Earth and heading for space. Growing up in today's world, it can be hard to imagine a time when outer space was a true mystery. You already know men have walked on the Moon. The International Space Station orbits Earth and sends back all sorts of information.

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Do you ever dream of traveling through outer space? Would you like to orbit Jupiter? Visit Pluto? Maybe you imagine racing past other planets and galaxies on a adventure. If you've ever looked into becoming an astronaut, there's one name you probably already know-NASA!

NASA (National Aeronautics and Space Administration) is the United States space . It's the group that put the first man on the moon. It has sent spacecraft to Mars and even Jupiter without humans on board. NASA continues to look deeper into space every day with the Hubble Telescope. But have you ever WONDERed just how NASA started?

Many of our Wonder Friends have read about the Cold War. It was a very long between the United States and the U.S.S.R. In October 1957, as it was still going on, the U.S.S.R. launched Sputnik. That made it the first nation to put a satellite in space. This pushed the U.S. to increase its efforts in space exploration .

As a result, President Dwight D. Eisenhower legislation to NASA in 1958. After some changes by Congress, the organization became official in July of that year. T. Keith Glennan became its first administrator on August 19, and NASA opened on October 1.

Of course, the rest is history. NASA soon became a world leader in space exploration . Its astronauts became some of the most famous in the world. Maybe you've heard of some of them! There's John Glenn, the first American to orbit the Earth. And of course Neil Armstrong, the first person to walk on the moon.

Many other NASA astronauts broke barriers when they traveled into space. In 1983, Guion Bluford became the first Black American in space. That same year, Sally Ride traveled into space. She was the youngest American and first American woman to do so. Mae Jemison became the first Black American woman in space in 1992.

What's next for NASA? It is continuing its work on the International Space Station ( ISS). It's also working with private companies, Boeing and SpaceX, to make commercial spacecraft.

A NASA project called Artemis is hoping to return to the moon by 2024. There, scientists hope to further study the moon and test technology there. How about the Red Planet? NASA plans to return to Mars in the coming years- and it's bringing a helicopter.

NASA has accomplished a lot in the last several decades. What if you were in charge? What part of the would you set your sights on? Maybe you would plan a trip to Saturn. How about the Andromeda galaxy? The possibilities are as vast as space itself!

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Do you ever dream of traveling through outer space? Would you like to orbit Jupiter? Visit Pluto? Maybe you imagine racing past other planets and galaxies on a adventure. If you've ever looked into becoming an astronaut, there's one name you probably already know-NASA! NASA (National Aeronautics and Space Administration) is the United States space .

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In this activity, students learn the cardinal points of the compass. They also learn how to use the Sun and star constellations - the Southern Cross and the Pointers - to identify the cardinal compass points.

By the end of this activity, students should be able to:

recall the cardinal compass points

explain how the compass points relate to the South and North Poles

use the rising or setting Sun to determine east and west (and therefore north and south)

locate the Southern Cross

use the Southern Cross and the Pointers to locate the Southern Celestial Pole (SCP)

use the Southern Cross to determine compass points and therefore direction.

Download the Word file (see link below) for:

introduction/background notes

what you need

what to do

student handout.

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In this activity, students learn the cardinal points of the compass. They also learn how to use the Sun and star constellations - the Southern Cross and the Pointers - to identify the cardinal compass points.

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The Stars and Planets in our Solar System

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The Stars and Planets in our Solar System

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The Solar System is made up of the Sun and all of the smaller objects that move around it. Apart from the Sun, the largest members of the Solar System are the eight major planets. Nearest the Sun are four fairly small, rocky planets - Mercury, Venus, Earth and Mars.

Beyond Mars is the asteroid belt - a region populated by millions of rocky objects. These are left-overs from the formation of the planets, 4.5 billion years ago.

On the far side of the asteroid belt are the four gas giants - Jupiter, Saturn, Uranus and Neptune. These planets are much bigger than Earth, but very lightweight for their size. They are mostly made of hydrogen and helium.

Until recently, the furthest known planet was an icy world called Pluto. However, Pluto is dwarfed by Earth's Moon and many astronomers think it is too small to be called a true planet.

An object named Eris, which is at least as big as Pluto, was discovered very far from the Sun in 2005. More than 1,000 icy worlds such as Eris have been discovered beyond Pluto in recent years. These are called Kuiper Belt Objects. In 2006, the International Astronomical Union decided that Pluto and Eris must be classed as "dwarf planets".

Even further out are the comets of the Oort Cloud. These are so far away that they are invisible in even the largest telescopes. Every so often one of these comets is disturbed and heads towards the Sun. It then becomes visible in the night sky.

Last modified 07 August 2014

Related articles

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The Solar System is made up of the Sun and all of the smaller objects that move around it. Apart from the Sun, the largest members of the Solar System are the eight major planets. Nearest the Sun are four fairly small, rocky planets - Mercury, Venus, Earth and Mars.

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Far-Out Facts

* Our solar system's eight planets come in two flavors: smaller rocky planets with solid ground ( Mercury, Venus, Earth and Mars) and larger gas giants ( Jupiter, Saturn, Uranus, and Neptune).

* You can spot six of the solar system's planets with the naked eye from Earth-and all eight if you have binoculars or a telescope.

* Astronomers have discovered hundreds of worlds beyond our solar system and are spotting more every day. Scientists believe some of these "exoplanets" may support alien life. Who knows. Maybe an alien kid elsewhere in the galaxy is wondering if you exist.

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Video Transcript

There was once a time when you could take a stroll from North or South America to Africa no problem. There was no ocean to get in the way, because all of Earth's continents were stuck together in one massive supercontinent called Pangea.

But around 180 million years ago, a rift began to form, and since then, the Americas and Africa have been drifting apart, forming the Atlantic Ocean in the process.

Weird, right?

Despite its rock-solid appearance, Earth's surface is constantly shifting and drifting. That's thanks to something called plate tectonics.

Unlike other planets, Earth's crust isn't simply a single shell. It's got big slabs of crust called tectonic plates that float on an ocean of slowly flowing rubbery molten rock.

These plates move because of heat from Earth's core. Earth's radioactive core generates an immense amount of heat that keeps our planet from completely cooling over.

Less dense molten rock travels from the core to the surface, where it then cools and returns-a process called convection.

Like a slowly moving conveyor belt, this rising and sinking heat and molten rock pushes or pulls the plates together or apart.

Through collisions, these plates can raise great mountains or send ocean floor to the depths of Earth's molten interior. When they move apart, new crust is formed, and with it, entirely new oceans can be created.

The formation of new ocean crust occurs at volcanic 'mid-ocean ridges.' The destruction of old ocean floor happens in 'subduction zones.' The creation and destruction of seafloor ultimately drives the gradual shift in the arrangement of continents on Earth.

It's a slow process. The Atlantic Ocean gets less than an inch of new seafloor each year. But that adds up over time. Scientists think that it could be possible to walk across a single, Pangea-like continent once again-in just a couple hundred million years...

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Student Video: Space Place in a Snap: Tectonic Forces | NASA/JPL Edu

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There was once a time when you could take a stroll from North or South America to Africa no problem. There was no ocean to get in the way, because all of Earth's continents were stuck together in one massive supercontinent called Pangea.

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Research a natural or man made disaster:

Key questions:

What challenges did this disaster present?

What opportunities came from the disaster?

How was the environment/people affected?

How was the disaster managed?

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Investigating the rock cycle

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There are three main types of rocks: sedimentary, igneous, and metamorphic. Each of these rocks are formed by physical changes-such as melting, cooling, eroding, compacting, or deforming-that are part of the rock cycle.

Sedimentary rocks are formed from pieces of other existing rock or organic material. There are three different types of sedimentary rocks: clastic, organic (biological), and Sedimentary Rocks chemical. Clastic sedimentary rocks, like sandstone, form from clasts, or pieces of other rock. Organic sedimentary rocks, like coal, form from hard, biological materials like plants, shells, and bones that are compressed into rock.

The formation of clastic and organic rocks begins with the weathering, or breaking down, of the exposed rock into small fragments. Through the process of erosion, these fragments are removed from their source and transported by wind, water, ice, or biological activity to a new location. Once the sediment settles somewhere, and enough of it collects, the lowest layers become compacted so tightly that they form solid rock.

Chemical sedimentary rocks, like limestone, halite, and flint, form from chemical precipitation. A chemical precipitate is a chemical compound-for instance, calcium carbonate, salt, and silica-that forms when the solution it is dissolved in, usually water, evaporates and leaves the compound behind. This occurs as water travels through Earth's crust, weathering the rock and dissolving some of its minerals, transporting it elsewhere. These dissolved minerals are precipitated when the water evaporates.

Metamorphic rocks are rocks that have been changed from their original form by immense heat or pressure. Metamorphic rocks have two classes: foliated and nonfoliated. When a rock with flat or elongated minerals is put under immense pressure, the minerals line up in layers, creating foliation. Foliation is the aligning of elongated or platy minerals, like hornblende or mica, perpendicular to the direction of pressure that is applied. An example of this transformation can be seen with granite, an igneous rock. Granite contains long and platy minerals that are not initially aligned, but when enough pressure is added, those minerals shift to all point in the same direction while getting squeezed into flat sheets. When granite undergoes this process, like at a tectonic plate boundary, it turns into gneiss (pronounced "nice").

Nonfoliated rocks are formed the same way, but they do not contain the minerals that tend to line up under pressure and thus do not have the layered appearance of foliated rocks. Sedimentary rocks like bituminous coal, limestone, and sandstone, given enough heat and pressure, can turn into nonfoliated metamorphic rocks like anthracite coal, marble, and quartzite. Nonfoliated rocks can also form by metamorphism, which happens when magma comes in contact with the surrounding rock.

Igneous Rocks Metamorphic Rocks

Igneous rocks (derived from the Latin word for fire) are formed when molten hot material cools and solidifies. Igneous rocks can also be made a couple of different ways. When they are formed inside of the earth, they are called intrusive, or plutonic, igneous rocks. If they are formed outside or on top of Earth's crust, they are called extrusive, or volcanic, igneous rocks.

Granite and diorite are examples of common intrusive rocks. They have a coarse texture with large mineral grains, indicating that they spent thousands or millions of years cooling down inside the earth, a time course that allowed large mineral crystals to grow.

Alternatively, rocks like basalt and obsidian have very small grains and a relatively fine texture. This happens because when magma erupts into lava, it cools more quickly than it would if it stayed inside the earth, giving crystals less time to form. Obsidian cools into volcanic glass so quickly when ejected that the grains are impossible to see with the naked eye.

Extrusive igneous rocks can also have a vesicular, or "holey" texture. This happens when the ejected magma still has gases inside of it so when it cools, the gas bubbles are trapped and end up giving the rock a bubbly texture. An example of this would be pumice.

Director

Tyson Brown, National Geographic Society

Author

National Geographic Society

Production Managers

Gina Borgia, National Geographic Society

Jeanna Sullivan, National Geographic Society

Program Specialists

Sarah Appleton, National Geographic Society, National Geographic Society

Margot Willis, National Geographic Society

Last Updated

October 19, 2023

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The rock cycle is a series of processes that create and transform the types of rocks in Earth's crust.

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As a terrestrial planet, Earth is divided into layers based on their chemical and rheological properties. And whereas its interior region - the inner and outer core - are mostly made up of iron and nickel, the mantle and crust are largely composed of silicate rock. The crust and upper mantle are collectively known as the lithosphere, from which the tectonic plates are composed.

It in the lithosphere that rocks are formed and reformed. And depending on the type of rock, the process through which they are created varies. In all, there are three types of rocks: igneous, sedimentary, and metamorphic. Each type of rock has a different origin. Therefore, the question, "How are rocks formed?" begs three distinct answers.

How Are Igneous Rocks Formed?

Igneous rocks are formed when melted rock cools and solidifies. Melted rock may come in the form of magma, when it is found underneath the Earth's surface. It can also come in the form of lava, when it is released unto the Earth's surface during a volcanic eruption. Some examples of igneous rocks are granite, scoria, pumice, and obsidian.

Pumice, for instance, is formed when lava made up of melted rock, water, and trapped gas is ejected from a volcano during a violent eruption. As the ejected material undergoes very rapid cooling and depressurization, some of the trapped gas escape, leaving holes and gas bubbles on the solidified material.

How Are Sedimentary Rocks Formed?

Sedimentary rocks start forming when soil and other materials on the Earth's surface are eroded and finally settle down, forming one layer of sediments. As time passes, more and more materials get eroded and settle on the older layers. Thus, layer upon layer is formed. The lower layers undergo intense pressure due to the weight of the upper layers, eventually evolving into rocks.

Some examples of sedimentary rocks are sandstone, limestone, shale, conglomerate, and gypsum. Sandstone, for instance, is a result of depositions of sand from beaches and rivers. You can find them mostly in deltas, since this is where the rivers flow into the ocean.

How Are Metamorphic Rocks Formed?

To metamorphose or simply to morph means 'to change in form'. Metamorphic rocks are actually products of rocks that have undergone changes. Thus, a metamorphic rock may have originally been an igneous, sedimentary, or even another metamorphic rock. The changes occur when the original rocks are subjected to extreme heat and pressure beneath the Earth's surface.

They may also occur when the the original rocks are caught in the middle of two colliding tectonic boundaries. Some examples of metamorphic rocks are marble, slate, schist and gneiss. Marble, for instance is the result of the metamorphism of limestone and dolostone. When limestone metamorphoses, its calcite grains grow and interlock with one another. As such, marble is denser and harder compared to limestone.

We've written many articles about rocks here in Universe Today. For example, here's Igneous Rocks: How Are They Formed?, What Are The Earth's Layers?, What is the Earth's Mantle Made Of?, After 40 Years Moon Rocks Still Revealing Secrets, Two New Kinds of Moon Rocks Found, Rocks From Mars.

For more information on Moon Rocks, check out NASA's Earth Observatory.

Astronomy Cast also has some interesting episodes on the subject. Here's Episode 113: The Moon - Part I and Questions Show: Shooting Lasers at the Moon and Losing Contact with Rovers

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As a terrestrial planet, Earth is divided into layers based on their chemical and rheological properties. And whereas its interior region - the inner and outer core - are mostly made up of iron and nickel, the mantle and crust are largely composed of silicate rock.

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Scientists have found how planet formation occurs

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Why are earthquakes so hard to predict? - Jean-Baptiste P. Koehl

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Volcanic eruption explained - Steven Anderson

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The colossal consequences of supervolcanoes - Alex Gendler

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Supervolcanoes 101 | National Geographic

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The incredible collaboration behind the International Space Station - Tien Nguyen

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Could we survive extended periods of time in space?

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Could we survive extended periods of time in space?

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Could we survive prolonged space travel? - Lisa Nip

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What it's like to live on the International Space Station | Cady Coleman