The extremely broad topics of life, what it is and how it started, and of our own planet’s existence are described and explained.  Clear and easily understood information is presented about how certain conditions must be met for an astounding variety of life to exist.  Scientists propose that not only may life exist in other places in our solar system but in places outside our system (exoplanets) as well.  Stunning photographs, illustrations, and charts are captioned and many side bars provide related information.  One learns how closely seemingly unrelated circumstances are required for other types of life to exist.  This book provides a great, basic understanding of known truths, as of today, which encourages further thinking and research.  In the back are:  a timeline of planet discoveries and how exoplanets are named, a glossary, index, many other books to read, and an extensive list of websites.  Excellent resource for classroom and middle school libraries.