Life is a property of the universe. We may not know how it began or where else it exists, but we have come to know a great deal about how it relates to stars, planets, and the larger cosmos. In clear and compelling terms, this book shows how the emerging field of astrobiology investigates the nature of life in space. How did life begin? How common is it? Where do we fit in? These are the important questions that astrobiology seeks to answer.