The atmosphere consists of several layers of colorless gases such as hydrogen and helium. From lower to higher, the layers are:

• troposphere: from the planet surface to roughly 7-17 kilometers up. It makes up about 75% of the atmosphere. Weather occurs here, through exchanges of heat. The outer boundary is called the tropopause;
• stratosphere: reaches up to about 50 kilometers, where the stratopause is. Includes the ozone layer;
• mesosphere: 50-85 kilometers up to the mesopause. Meteorites break up here;
• thermosphere: to 640 kilometers up. Auroras appear here. The layer of molecules broken up--ionized--by particles from the sun is the ionosphere that makes radio work by bouncing radio waves back to the Earth;
• exosphere: merges with space.