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Ten Things to Know About Earth

1: MEASURING UP

If the Sun were as tall as a typical front door, Earth would be the size of a nickel.

2: THIRD ROCK

Earth orbits our Sun, a star. Earth is the third planet from the Sun at a distance of about 93 million miles (150 million km).

3: AS THE WORLD TURNS

A day on Earth is 24 hours. Earth makes a complete orbit around the sun (a year in Earth time) in about 365 days.

4: WE'RE ON IT

Earth is a rocky planet with a solid and dynamic surface of mountains, canyons, plains and more. Most of our planet is covered in water.

5: BREATHE EASY

Earth's atmosphere is 78 percent nitrogen, 21 percent oxygen and 1 percent other ingredients—the perfect balance to breathe and live.

6: OUR COSMIC COMPANION

Earth has one moon.

7: RINGLESS

Earth has no rings.

8: ORBITAL SCIENCE

Many orbiting spacecraft study the Earth from above as a whole system—observing the atmosphere, ocean, glaciers, and the solid earth.

9: HOME, SWEET HOME

Earth is the perfect place for life as we know it.

10:PROTECTIVE SHIELD

Our atmosphere protects us from incoming meteoroids, most of which break up in our atmosphere before they can strike the surface.