In this highly readable yet solidly scientific book, distinguished planetary scientist John S. Lewis brings us the latest results of the search for new planets in our galaxy. Worlds Without End is both a grand tour of the solar system and a fascinating look at the many theories of planet formation and of life on earth. Lewis explains how planets form, what they are made of, and how scientists know what they know about them. Lewis examines the evidence for the existence of planets orbiting distant suns, including gigantic planets that orbit their suns even closer than Mercury circles our own sun. By examining what we know about the planets in our own solar system, Lewis shows how that knowledge, built up over decades of astronomical observations, robot explorers, and manned space missions, can help us determine what kinds of planets those distant ones are likely to be, and what kind of life we can expect to find on them.