This textbook gives a lively introduction to the search for extraterrestrial life. It is a guidebook to understanding the possibility of life elsewhere, pointing out landmarks and providing background information to facilitate further exploration of those areas of most interest to the reader.

We are a planet of winners – winners of a cosmic lottery that has been in play since the universe began approximately 13.7 billion years ago. Our winnings include sentience and an underlying unease that has driven us to contemplate our place in the universe and the possibility of finding kindred spirits in the cosmos spreading out before us. To understand our origins and the possibility of life beyond Earth, we must look back and retrace the steps that have brought us to this point in space and time. In doing so, we will find the investigation of life to be a unifying theme in nature, requiring us to touch on all branches of the tree of knowledge. Using the Drake Equation as a theme, we begin with an overview of the topic and then go into the story of how we have acquired, or plan to acquire, the knowledge to solve it. As we make our journey, we will encounter some very interesting people – some you will likely know, while others may be new to you. Keep an open mind and allow this text to be your guide.

Written in an engaging style, this textbook provides a foundational understanding of the rapidly advancing fields associated with the search for life in the universe. Each chapter includes illustrative figures and review questions for self-study. It will appeal to professionals, researchers, instructors, and undergraduate students, as well as anyone with an interest in astrophysics or astrobiology.