During the formation of the Sun conditions in protoplanetary disk were not, of course, the same at different distances from the Sun and have changed over time. The matter remained cold just away from the Sun. Near him was strongly heated and dust suffered complete or partial evaporation. Only later, when the gas is cooled down, she condense again, but most volatile substances contained in interstellar dust appeared to be lost in the new dust is not already included. The evolution of the protoplanetary disk led to the formation in it of planetesimals, which later grew planet. The composition of planetesimals formed at different heliocentric distances, due to the different composition of dust, gone to their building, was different.

It just so happens that the asteroid is planetesimals formed on the border of the hot and cold areas of the protoplanetary disk, preserved to our days. Although the ring of asteroids has a small extent (about 1 and. E.), the difference of conditions it was apparently enough to form different from each other S - and P-asteroids. It is logical to think that's-asteroids formed in a warmer area on smaller heliocentric distances than the asteroids, and now slowly shuffled. However, as is generally the only ones left of the body, which formed on the most ustoichivyh orbits, full mixing them for the past 4.5 billion years did not happen. So still-asteroids gravitate to the external case ring and S-asteroids - to untrendy. But, facing each other, they contaminate the surface of each other with their substance, and, probably, so the color of the S - and C-asteroids is slowly changing with heliocentric distance.

Asteroids was formed in protoplanetary cloud as loose aggregates. A small force of gravity could not compress the deepening of dust planetesimals. Due to the radioactive heat they warmed up. This warm-up, as shown by calculations, J. Wood, was very effective : it loose body good at keeping you warm. Warm-up began in the growth stage of asteroids. Their substance in the Central parts warmed himself, had had it, and maybe even melted, and on the surface of asteroids was still sleep in the dust, adding to loose, heat insulating layer. The main source of heating is now considered to be aluminium-26, the aluminium-26, who in a million years before the formation of the asteroids were injected with a substance of a supernova star in protocolecho nebula.

The collision of asteroids between them at first also led to the compression of matter. Asteroids was compact bodies. But further disturbance from increased lanet led to increase of the speed with which clashes occurred. As a result, more or less compact body were broken. The collision was repeated many times, granulating, shaking, stirring, welding debris and again granulating. That is why modern asteroids are probably poorly Packed blocks.

To the earth's orbit small asteroid fragments, do, of course, from a ring of asteroids. This is due not quite clear in details the mechanism sequential resonant excitation of orbits under the action of planetary perturbations. But the buildup occurs only in some areas of the rings. Asteroids from different places rings do differently now, and debris in the vicinity of earth's orbit may not be representatives of those objects that are moving beyond the orbit of Mars.

And in the earth's atmosphere only survive the slowest and most durable of them, leading to a further selection. Therefore, in our collections, undoubtedly, are missing many species asteroid substance, and it is possible that the idea of an asteroid substance, as a matter of dense and compact, not that other, as obsolete, inspired by meteorites misleading.