What keeps objects from floating out of your hand? What if your feet drifted away from the ground? What stops everything from floating into space? Gravity. As in his previous books, Redwoods, Coral Reefs, and Island, Jason Chin has taken a complex subject and made it brilliantly accessible to young readers in this unusual, innovative, and very beautiful book.

You have probably seen movies or television shows about space travel. When space travelers go outside their ships, they use jet packs to tie themselves to their ships. They do this because outside their spaceships there is no force that keeps them attached to the craft. Without something to keep them attached, they would just drift off into space because there is no gravity. Gravity is also the reason why our bodies don't just fly upward into...