The question about the possible structure of outer (beyond Neptune) regions of the solar systems is studied within the scope of the new cosmogony model of formation of planetary systems (Eneev and Kozlov, 1977, 1979). The analysis of the problem of Pluto's origin is the basis of this study. It is noted that under certain conditions the evolutionary process in some accumulation zones of the protoplanetary cloud may lead to the formation of an asteroid belt but not to the formation of a planet. The hypothesis is stated that during the solar system formation such conditions existed beyond Neptune's orbit and that at present unknown asteroid belts exist in this region. Pluto is assumed to be an asteroid of one of these belts. The question is discussed about evolutionary consequences of formation of outer asteroid belts. It is noted that the part of bodies must inevitably migrate from the asteroid belts into the regions lying within Neptune's orbit, and these bodies must take a respective effect upon the subsequent evolution of planets and their orbits. In particular, the attention is paid to the possible existence of the connection between the above migration of asteroid bodies and the resonant relations in the solar system.

Theoretical and applied problems of mechanics