Vistas in Astronomy, Volume 11 provides information pertinent to the periodic movements of the bodies of the solar system. This book discusses the apparent motion of Sun and stars. Organized into 13 chapters, this volume begins with an overview of the values of terrestrial and astronomical refraction that are deduced from the lunar sites themselves. This text then discusses the unit of time based on the ephemeris of the Sun whereby the advantages of precision and availability are being sacrificed in the interest of uniformity. Other chapters consider the unit of time and the measurement of long intervals. This book discusses as well the mathematical formulation of the eigenvibrations of an elastic sphere. The final chapter examines the orientation s in space of stellar-angular-momentum vectors in the light of empirical data, and their origin is then explained by simple models. This book is a valuable resource for astronomers and astrophysicists.