Astronomy and Astrophysics is a comprehensive, fundamental, and up-to-date reference book. It is filled with vital information and basic facts for amateur astronomers and professional astrophysicists, and for anyone interested in the Universe, from the Earth and other planets to the stars, galaxies and beyond. An exceptionally thorough Index cross-references concepts, discoveries and individuals in both the Timeline section and Dictionary section. The combined result is a unique stand-alone reference volume in which the reader can quickly locate information, while also discovering new and unexpected knowledge.