In recent years the fields of both particle physics and astrophysics have become increasingly interdependent. Experiments in particle physics at terrestrial accelerators are complementary to sources and accelerators in the Cosmos, while astrophysicists have found that an understanding of relativity and particle physics is essential to describe many of the most interesting observed phenomena and for a detailed description of the early Universe. This book provides a graduate level introduction to the new field of particle astrophysics. It describes the close connection between the microcosm (particles) and the macrocosm (Universe). The approach is wide ranging and succeeds in introducing all the major theoretical concepts as well as describing the most recent experimental and observational evidence in the field. As such it will be invaluable to anyone approaching the subject from either particle physics or astrophysics. For this revised paperback edition the authors have taken the opportunity to make corrections and bring the book up to date in this rapidly developing and exciting field.