Asteroids----A small but numerous group

In the Solar system, the Sun and nine planets always catch our attention. Actually, there is a small but numerous group, asteroids, often being ignored by us.

The number of asteroids is big amounting to 5,000 - 6,000. It is possible to discover new asteroids. Most asteroids are located with Mars and Jupiter and they also revolve to the Sun. Some asteroids are located inside the orbit of the Earth and very close to the Earth.

How small are these asteroids? The largest ones are about 1,000 kilometers in diameter and most of them have the diameter less than 100 kilometers. The smaller they are, the higher quantity they have. The size is very small comparing with that of nine planets.

Most asteroids are flat circles. Some are like meteors and some have the features of comet plate. At the beginning stage of the Sun's formation, many asteroids collide to each other and became planets and the rest became asteroids. But some believe asteroids were formed by bombardment.