Topical Problems in the Theory of Planet Formation: Formation of Planetesimals

We consider the history of the development of the theory of the formation of the Earth and planets over 70 years with special emphasis placed on the development of this theory at the Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences (IPE RAS), where Otto Schmidt founded this direction of research. The current state of the theory is reviewed. In particular, we discuss the problem of the formation of planetesimals, currently belonging to the key unsolved problems in the theory of planet formation. We present the results of the recent studies carried out at IPE RAS aimed at solving this problem.