Comets are celestial objects that orbit the sun. They're comprised of frozen gases, rock, and dust. When a comet hurtles near the sun, its dusts and gases heat up and form a halo and a tail. Your intrepid explorers will learn the scientific history of discovering and identifying comets and the difference between comets and other space objects. Photographs and artist renderings of comets and their paths help readers understand these amazing astronomical phenomena.