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Description
Flashcards by ellie_woodward, updated more than 1 year ago
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Created by ellie_woodward
about 9 years ago
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| Question | Answer |
| There are eight planets orbiting the sun in almost circular paths (ellipses.) Closest to the sun are the inner planets- Mercury, Venus, Earth and Mars. Then we have the asteroid belt. Then, the outer planets, which are much further away from the sun; Jupiter, Saturn, Uranus, and Neptune. | There are also various other things- Dwarf planets, comets, dust, and so on- all in orbit around the sun. Planets also often have moons orbiting them- they're usually much smaller and found close to the planet. These also count as part of the solar system. |
| You can see some planets with the naked eye. They look like stars, but they're totally different. Stars are huge (the Sun's diameter is over 100 times bigger than than the Earth's), very hot, and very far away. They give out lots of light- which is why you can see them even though they're far away. | Planets are much smaller and they just reflect sunlight allying on them. The planets in the solar system are also much closer to us that any other star (except the sun). Stars and Planets are very different from each other. |
| The solar system is about 5 thousand million years old. The solar system was formed over a very long period of time from big clouds of dust and gas. For some reason, one cloud started to get squeezed slightly. | Once the particles had moved a bit closer to each other, gravity took over. It pulled things closer together until the whole cloud started to collapse in on itself. At the centre of the collapse, particles came together to form a protostar. |
| When the temperature got high enough, a process called fusion started- hydrogen nuclei joined together to make helium. Fusion gives out massive heat and light, so a star, our sun, was born. (The sun and other stars' energy comes from the fusion of hydrogen nuclei.) | All of the chemical elements in the clouds with heavier atoms than helium and hydrogen were also formed in the stars by the fusion of different nuclei. Around the sun, material from the cloud containing hydrogen, helium and heavier elements started to clump together, and these clumps became planets. |
| The oldest rock on earth is actually meteorites (rocks from space that crashed into earth- we think they were formed not long after the birth of the solar system). They are about 4500 million years old- so we know that the solar system is at least that old. | Asteroids and Comets are smaller than most plants, and are made of stuff left over from the formation of the solar system. The rocks between Mars and Jupiter didn't form a planet, but stayed as small lumps of rubble and rock- these are asteroids. |
| Comets are balls of rock, dust, and ice which orbit the sun in very elongated ellipses, often in different planes from the planets. The sun is near one end of the orbit. | As a comet approaches the sun, its ice melts, leaving a bright tail of gas and debris which can be millions of kilometres long. That is what we can see from earth. |
| We're in the milky way galaxy. Our sun is one of thousands of millions of stars which form the milky way galaxy- about 1 in 100 000 000 000 (or 10 to the power of 11) if you had to write it out. The sun is about half way along one of the spiral arms of the milky way. | The distance between neighbouring stars in a galaxy is usually millions of times greater than the distance between planets in the solar system. |
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