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Asteroids: FAQ
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Asteroids orbit the sun in region of space known as the asteroid belt, which is located between the orbits of Mars and Jupiter.

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Yes, but they do not pose a threat to life on Earth. About once a year an automobile-sized asteroid enters Earth's atmosphere, creates an impressive fireball and disintegrates before ever reaching the surface.

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It is believed that a giant asteroid caused the extinction of the dinosaurs.

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The largest asteroid is asteroid Ceres at about 952 km (592 miles) in diameter. Ceres is so large that it is also categorized as a dwarf planet.

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Asteroids range in size from about 952 km (592 miles) in diameter (asteroid Ceres), to bodies that are less than 1 km (0.6 mile) across.

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Several NASA space missions have flown and observed asteroids. The NEAR Shoemaker mission landed on an asteroid in 2001 and NASA's Dawn mission was the first mission to orbit an asteroid (2011).

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Possibly, however there are no planned human missions to an asteroid at this time.

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Yes. More than 150 asteroids are known to have a small companion moon (some have two moons).

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No, asteroids do not fit the criteria set forth by the International Astronomical Union (IAU) for a planet. However, one asteroid (Ceres) within the asteroid belt is considered a dwarf planet.

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Asteroids are believed to be mostly composed of clay, silicate and nickel-iron.

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Yes, two missions have landed on two different asteroids. NEAR Shoemaker (NASA) landed on asteroid Eros in 2001 and Hayabusa (JAXA) landed on asteroid Itokawa in 2005.

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Last Updated: 13 May 2014