Location: Scattered around the solar system, with most in the asteroid belt between Mars and Jupiter

Diameter: From about 1/2 mile to hundreds of miles across

Number: Estimated at ~100,000

Asteroids are made of rock and metal.

The Galileo spacecraft took pictures of this asteroid, Gaspra, in 1991 on its way to Jupiter.

Asteroids are large rocks that orbit the Sun. There are thousands of asteroids that travel around the Sun in a belt between the orbits of the planets Mars and Jupiter. Asteroids are usually so small and far away that they are difficult to see. Ceres, the largest asteroid, is nearly 560 miles across. Gaspra is brown and grey.

[next page]

The source of this material is Windows to the Universe, at from the National Earth Science Teachers Association (NESTA). The Website was developed in part with the support of UCAR and NCAR, where it resided from 2000 - 2010. © 2010 National Earth Science Teachers Association. Windows to the Universe® is a registered trademark of NESTA. All Rights Reserved. Site policies and disclaimer.