A student-active introduction to astronomy, emphasizing inquiry learning so students will clearly understand our universe and the scientific method. Within-text and end-of-chapter questions check understanding of concepts and require the student to think critically through astronomy-based problems. ‘Nature of Science' and 'Detectives on the Case' sections in each chapter encourage students to take on the role of a scientist and so develop an understanding of how scientific progress is made, leading students through a chain of arguments of forming and testing hypotheses, in the context of specific astronomical topics. By focusing on key topics, the student is able to develop a deeper understanding of the core areas of astronomy. Math is used to make intuitive points and kept simple by using a two-track system to first describe the logic of the calculation followed by a more detailed example. Simple illustrations support the text and step students through concepts visually.