Astronomy is one of the most rapidly advancing fi elds in modern science. Its subject matter intrigues many students and simultaneously challenges textbook authors to keep up with the most recent discoveries, interpretations, and defi nitions. We built this textbook and its supporting media package with one goal in mind: to help students understand the world around them through the eyes of a scientist. Students who study introductory astronomy typically come from diverse backgrounds; often their introductory astronomy course is the only formal exposure to science they will have in their lives! As instructors, everything we do should turn on the answer to basic questions such as these: What should students carry away from this course that will still be with them 20 years from now? How should this course change the students who take it? And how can we, as scientists and educators, facilitate those changes within our students?