Translated from the Russian by G. YankovskyAn accessible exposition of gravitation theory and celestial mechanics, this classic, oft-cited work was written by a distinguished Soviet astronomer. It explains with exceptional clarity the methods used by physicists in studying celestial phenomena.A historical introduction explains the Ptolemaic view of planetary motion and its displacement by the studies of Copernicus, Kepler, and Newton. Succeeding chapters examine the making of celestial observations and measurements and explain such central concepts as the ecliptic, the orbital plane, the two- and three-body problems, and perturbed motion. Ryabov also describes how perturbations in the path of Uranus led to the discovery of Neptune, and he devotes considerable attention to satellites, including a detailed treatment of the first artificial satellite, Sputnik I. Additional topics include planetary rotation, the calculation of units of time, and the motions of the stars, with illustrations of how the law of gravity determines the shapes of galaxies. The book concludes with a deeper consideration of gravity, pointing out basic distinctions between classical and Einsteinian theories. Introduction  Ancient Conceptions  Concerning the Motions of the Sun, Moon, Planets and Stars  The Geometry of Planetary Motions from Copernicus to Kepler  The Discovery of the Law of Gravitation  The Attraction of Material Bodies of Different Shapes  Experimental Detection of Attraction between Material Bodies on Earth  Newton's Law---The Theoretical Basis of Celestial Motion  Celestial Motion and the Two-Body Problem  The Concept of Perturbed Motion.  Celestial Mechanics and Practical Astronomy  Ways of Describing Perturbed Motion.  The Variational Orbit  The Problem of Motion in the Solar System  Succes sive Approximations in the  Theory of Motion of Heavenly Bodies  The Discovery of Neptune  Periodic and Secular Perturbations  Numerical Methods in Celestial Mechanics  Satellite Theory  Artificial Earth Satellites and Their Motion  The Motions of Asteroids  Planetary Rotation  Problems of Qualitative Celestial Mechanics  Stellar Motions and the Law of Gravitation  What is Gravitation? Appendix