The beginning of the 19th century. In Palermo, in Sicily, Italian astronomer by gioseppe Piazzi for many years led the observations of the positions of the stars for compiling star catalogue. The work was nearing an end. And now, the first night of the XIX century, on 1 January 1801, Piazzi discovered in the constellation Gemini weak star, with a brightness of about 7m, which for some reason was not in its own directory or in the directory Christian Mayer available to Piazza.

The next night it appeared that the asterisk is not the same coordinates that the day before she moved on 4" right ascension and 3",5 sentencing. On the third night it was found that there is no error and that the asterisk moves slowly across the sky. Six weeks of questioning Piazzi strange star. No disk, which should have a planet, not a dim view characteristic of comets! Then, the observations were interrupted by illness, Piazzi. Returning to the observations, he was unable to find Ceres, as was later named the new planet.

At this time, Carl Friedrich Gauss was engaged in development of methods of processing of astronomical observations. He decided to try to determine the elliptical orbit of the new planet, derived they method (in three cases). Thus, Gauss determined that the orbit of the object lies between the orbits of Mars and Jupiter, and that the semi-major axis it is 2.8. e.. It was a planet that I was looking for since, when it was discovered the so-called dependence of Titius-Bode, which distances of the planets from the Sun obey certain laws. According to this law, between the orbits of Mars and Jupiter must be another planet, which astronomers didn't watching. This regularity and pushed astronomers of the time to look this hypothetical planet, which later was named the Phaeton. However, too weak Shine Ceres talked about the fact that the size of this planet is very small compared to the major planets of the Solar system (according to current data dimensions of Ceres are h km, and it is the largest asteroid). Between Mars and Jupiter moved planet baby. It would seem that the planet is found, but on 28 March 1802 Heinrich Wilhelm Olbers unexpectedly near Ceres found another one, but weaker planet (about 9m). Olbers gave her name Pallada, in honor of Athena polias. Not only that Athena was moving too at a distance of 2.8. that is from the Sun, already occupied by Ceres, its orbit strongly deviated from the Ecliptic plane. After a lull in the discovery was followed by new discoveries of small planets at all the same average distance from the Sun 2.8 A.E. To 1860 was already known 62 of the asteroid, and by 1880 - 211 asteroid. And then new asteroids began to appear more and less. Later I discovered the asteroid with the magnitude 13-14m.

Fast forward to the 20th century. September-October 1960 Observatory On mount Palomar conducted systematic photographing small area of sky, located near the vernal equinox, i.e. near the Ecliptic, along which are moving asteroids. Two months was photographed about 2200 asteroids up to 20m, and for 1811 of them were able to determine the approximate orbit. Suppose that the total number of asteroids moving in the asteroid ring, from the largest to bodies with the diameter of 1 km reaches ONE MILLION (!). With all of this, the number of asteroids increases as the reduction of their sizes.