Book excerpt: 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. A truly interdisciplinary endeavor, astrobiology looks at the evidence of astronomy, biology, physics, chemistry, and a host of other fields. A grand narrative emerges, beginning from the smallest, most common particles yet producing amazing complexity and order. Lucas Mix is a congenial guide through the depths of astrobiology, exploring how the presence of planets around other stars affects our knowledge of our own; how water, carbon, and electrons interact to form life as we know it; and how the processes of evolution and entropy act upon every living thing. This book also reveals that our understanding and our context are deeply intertwined. It shows how much astrobiology can tell us about who we are—as a planet, as a species, and as individuals.