Astronomy: Structure of the Universe is the second of two textbooks written to meet the current need for a comprehensive and systematic treatment of astronomy, including the physical and mathematical groundwork so often omitted from other textbooks. Together with the introductory companion volume Astronomy: Principles and Practice it comprises a complete two-yeaer course in astronomy, while portions of the text may be selelcted as the basis of a preliminary science or liberal arts course at the first-year university level. Both books include many worked examples, problems with answers, and a selection of practical projects. Although primarily intended for undergraduate use, these books will also afford serious amateur astronomers a welcome opportunity to study their subject as a working science. This volume Astronomy: Structure of the Universe describes the observable features of the universe. The first part describes our Solar System and its members, giving special attention to the Sun, Earth and Moon. The second part treats the nature of matter and its behaviour in stellar bodies and interstellar matter under a wide range of physical conditions. The third part discusses our Galaxy in detail before considering external galaxies and ending with questions of cosmology and cosmogony. The third edition contains much new information derived from recent experiments and space missions. The text is updated throughout.