This calculus-based introductory text explains how and why certain astronomical phenomena occur and how astronomers collect and interpret information about stars and the solar system. Recent theories and findings in the field are incorporated, including particle physics and cosmology, results from recent observations of space, and new information on star formation, the galactic center, and dark matter. Descriptions are given of the nature and properties of stars; the cycle of stellar birth, life, and death; the nature of galaxies; and the overall structure of the universe. Throughout, the emphasis is on understanding phenomena by applying some basic physical principles to a variety of situations. The book contains extensive examples, useful equations, problem sets, chapter summaries, and test examples.