Astronomers confirmed the existence of planets outside our own solar system relatively recently--in 1992. Their long-anticipated discovery was hardly a surprise, but was quite a while in coming. Nobody has found an Earth-like world that is able to sustain life as we know it, but it seems only a matter of time before that happens. Meanwhile, Planet Quest explains the science behind the search for new planets. Readers who need to brush up on the basics of their own solar system will find a helpful introductory chapter, as well as an interesting discussion of why there is probably no "Planet X" orbiting the Sun beyond Pluto. The bulk of the book, of course, is devoted to extrasolar worlds and the planet hunters who seek them. (Amazon.com)