Click on image for larger version(175K GIF) Galileo image of Gaspra (29 October 1991) courtesy of NASA/JPL

Asteroids are small bodies that are believed to be left over from the beginning of the solar system 4,600 million years ago. They are rocky objects with strange shapes up to several hundred km across, but most are much smaller.

Many thousands of asteroids lie in a belt between Mars and Jupiter. Scientists think that this debris may be the remains of an early planet, which broke up early in the solar system. Several thousand of the largest asteroids in this belt have been given names.