"In Gravity: Mass, Energy, and the Force that Holds Things Together, scientists ages 8 to 12 explore the invisible but powerful force that is responsible for keeping the entire universe in place--including you! Gravity is the natural phenomenon that makes everything in the universe attracte dto everything else. On Earth, that means gravity is why we fall down toward the ground, the reason we have tides, and why we eigh a certain number of pounds."--...