Earth has an atmosphere. Not every planet does. It is the air around us. The layers form a "blanket." They protect us from the Sun. They also protect us from the cold of space.

Air contains many parts. It has nitrogen, oxygen, and small pieces of dust. Animals breathe oxygen. They get rid of carbon dioxide. Plants breathe carbon dioxide and get rid of oxygen. We find both in the air. We also find small amounts of other things. These can be natural or man-made.

The atmosphere is held in place by the pull of the Earth's gravity. It extends to about 1,250 miles above the surface of the planet.