Senior Contributing Authors: Andrew Fraknoi, Foothill College; David Morrison, NASA Ames Research Center; Sidney C. Wolff, National Optical Astronomy Observatory. Astronomy is designed to meet the scope and sequence requirements of one- or two-semester introductory astronomy courses. The book begins with relevant scientific fundamentals and progresses through an exploration of the solar system, stars, galaxies, and cosmology. The Astronomy textbook builds student understanding through the use of relevant analogies, clear and non-technical explanations, and rich illustrations. Mathematics is included in a flexible manner to meet the needs of individual instructors.