What has one head, sometimes has tails, and orbits the Sun? A comet! These giant balls of ice, mixed with rock and dust, orbit the Sun. When they are very far from it, they have no tails. When they get closer to the Sun, they heat up and give off a cloud of gases and dust--and form tails. Early readers will be taken on a journey through outer space in simple yet captivating text as they learn these and other fascinating facts about comets. Each 24-page...