Textbook in PDF format Astrophysics: Decoding the Cosmos, Second Edition, describes how information about the physical nature of stars and other celestial bodies is obtained and analyzed to gain a better understanding of the universe. This acclaimed introductory textbook makes the complex principles and theories underlying astrophysics accessible to students with basic knowledge of first-year calculus-based physics and introductory astronomy. Reader-friendly chapters explore physical processes using relevant examples and clear explanations of how radiation and particles are analyzed. Such analysis leads to the density, temperature, mass, and energy of astronomical objects