Thousands of asteroids lie in a belt between Mars and Jupiter. These asteroids lie in a location in the solar system where there seems to be a jump in the spacing between the planets. Scientists think that this debris may be the precursors of a planet, which was prevented from forming.
Asteroids are small boulders with either rounded or irregular shapes, which can be as large as a few football stadiums in size.
This is page 17 of 60