  We discuss problems of planetesimal migration in the emerging Solar System
and exoplanetary systems. Protoplanetary disk evolution models and the
formation of planets are considered. The formation of the Moon and of the
asteroid and trans-Neptunian belts is studied. We show that Earth and Venus
could acquire more than half of their mass in 5 million years, and their outer
layers could accumulate the same material from different parts of the feeding
zone of these planets. The migration of small bodies toward the terrestrial
planets from various regions of the Solar System is simulated numerically.
Based on these computations, we conclude that the mass of water delivered to
the Earth by planetesimals, comets, and carbonaceous chondrite asteroids from
beyond the ice line could be comparable to the mass of Earth's oceans. The
processes of dust migration in the Solar System and sources of the zodiacal
cloud are considered.
