First Pluto left. Then it came back, along with Ceres and Erisand now Haumea and MakeMake, too! The recent actions of the International Astronomical Union have put every solar system book out of date. In response, National Geographic joins forces with David Aguilar of the Harvard Smithsonian Astronomical Observatory to revise our 2008 book - and to update young readers on the high-interest topic of space. Using simple text and spectacular photorealistic computer art by the author, this book profiles all 13 planets in their newly created categories - plus the sun, the Oort Cloud, comets, and other worlds being discovered. Back-of-the-book activities offer hands-on fun for budding astronomers.