Each of the planets in our solar system is unique, with its own distinct size, composition, and atmosphere. From the searing heat of Mercury to the diamond rains of Neptune, readers learn about the characteristics of each planet as well as what criteria must be met for a body to be defined as a planet. This volume also explores the latest missions and discoveries from NASA and other space agencies. Stunning full-color photographs and detailed graphic organizers give students a fascinating glimpse at our celestial neighbors"--