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Our Solar System. Have you ever looked up into the sky and wondered what was there? Higher than

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the birds, past the clouds, and farther than the moon, a whole host of fascinating objects spin in

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outer space. Let's imagine for a moment that we can leave the earth behind and explore the solar

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system that surrounds it.

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We call it the solar system because everything in it is centered around the sun, and solar

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means something to do with the sun.

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The sun is a star, just like many of the stars that you can see in the night sky, just many

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times closer to us.

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Still, the sun is very, very far away from the earth, almost 93 million miles away.

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That's why it looks so small, even though it's the biggest object in the solar system.

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In fact, the Sun makes up more than 99% of the mass in the solar system.

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If you put all of the planets, moons, asteroids, comets, and everything else in the solar system

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together, they would make up less than one quarter of a percent of it.

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The Sun is so big that it's more than 100 times wider than the Earth, and if it were

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a giant jar, you could fit more than 1 million Earths into it.

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More than that, the Sun is what holds the solar system together.

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Its massive gravity is what keeps the Earth and all the other planets circling around

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it instead of drifting off into space.

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The Sun is also what allows us to live on Earth.

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Without the sun, there would be no heat, there would be no light, plants could not grow,

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water would freeze, and nothing could survive.

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The sun gives us heat and light because it is always burning.

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It is a giant ball of gas, mostly hydrogen and helium, and it burns at millions of degrees

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in its center.

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Let's leave the sun now, to explore the planets.