This easy-to-follow book offers a statistico-geometrical approach for dating ancient star catalogs. The authors' scientific methods reveal statistical properties of ancient catalogs and overcome the difficulties of their dating originated by the low accuracy of these catalogs. Methods are tested on reliably dated medieval star catalogs and applied to the star catalog of the Almagest. Here, the dating of Ptolemy's famous star catalog is reconsidered and recalculated using modern mathematical techniques. The text provides necessary information from astronomy and astrometry. It also covers the history of observational equipment and methods for measuring coordinates of stars. Many chapters are devoted to the Almagest, from a preliminary analysis to a global statistical processing of the catalog and its basic parts. Mathematics are simplified in this book for easy reading. This book will prove invaluable for mathematicians, astronomers, astrophysicists, specialists in natural sciences, historians interested in mathematical and statistical methods, and second-year mathematics students.