Asteroids is a small celestial body in size from a few metres to thousands of kilometres. In General, between them and meteoric bodies there is no clear difference. The number of such bodies in the Solar system more than they do less. Many scientists believe that most meteoroids are chips of asteroids. Asteroids, and meteorites consist of iron, Nickel and various stony rocks. They are close to the planets of terrestrial group.

Its name asteroids received for the similarity with the stars when observed through a telescope. Being a tiny asteroids appear as stars, points. The asteroid means "star-like".

Most asteroids are moving in the so-called asteroid belt between the orbits of Mars and Jupiter. Jupiter resent their movement. As a result, asteroids collide with each other, they change their orbits. Some of them may come closer to the Sun, or, conversely, to get away from him than most of the small planets.

Asteroids are occasionally faced with large planets. Many scientists believed to cause climate changes drastically, resulting in the extinction of the dinosaurs millions of years ago, was an asteroid hitting the Earth. On Earth even found a crater that could be formed from such a blow. I must say that the Earth has experienced several similar to "strange" extinctions of animals. For example, long before the dinosaurs as suddenly died out trilobites.

Beyond the orbit of Neptune found several celestial bodies with the size of 100-200 km Apparently, there too is the asteroid belt. He's called the Kuiper belt. The belt objects are more similar composition with comets than themselves asteroids. The orbit of Pluto passes already inside this zone.

In February 1997, it was suggested that beyond the orbit of Pluto at a distance of 50 AU, there is another asteroid belt. In it, as in the belt between the orbits of Mars and Jupiter, as in the Kuiper belt, as in the Oort Cloud, is unencumbered during the construction of the major bodies of the Solar system material. It is the presence of this belt proposed to explain the formation of the double planet Pluto-Charon, which, apparently, was formerly independent bodies. It is possible that in this zone there is a body larger than Pluto. The internal area of this zone cleared his inclination Neptune. Probably, that this belt of small bodies should not be confused with the Kuiper belt.

Perhaps in place of the asteroid belt between Mars and Jupiter rotates big planet, which is called the Phaeton. Tidal forces of Jupiter or catastrophic collision with a large celestial body, tore it into separate small pieces. The majority of scientists think that no planet was not that Jupiter its impact not just gave to gather together many of planetesimals - the embryonic planets in the early history of the Solar system. Whatever it was, and the total weight of all the bodies in the asteroid belt does not exceed the mass of the moon. A very large planet of all the asteroids could do it. It is assumed that there are about a hundred thousand asteroids inside the orbit of Jupiter, the available observations.