This book, which has been written by physicists, originated from the ancient problems of astronomy which are related to the shapes and evolution of celestial bodies and their systems.It has become a tradition among physicists to study individual fields of astrophysics. About 30 years ago this would have been a great event. At that time Professor D. A. Frank-Kamenetsky was one of the first Soviet physicists to begin to develop consistently the fundamental problems of astrophysics. Being a very erudite scientist he succeeded in influencing, by his passionate inquisitiveness, quite a number of young physicists who chose astrophysics as their speciality.We dedicate this book to the memory of D. A. Frank-Kamenetsky-a prominent scientist and a man of pure soul.

No abstract

No abstract

Cover picture: Voyager-I' image of Saturn and its rings taken Nov. 16. 1980, four days after its closest approach to Saturn, from a distance of 5 300 000 lan (3300 000 miles), This viewing geometry, which shows Saturn as a crescent, is never achieved from Eaith. The Satumian rings, like the cloud tops of Saturn itself, are visible because they reflect sunlight.