Thermosphere

Atmospheric layer above the mesosphere (above 85 kilometers) where air temperatures rise rapidly with height. The thermosphere is the hottest layer in the atmosphere. In the thermosphere, gamma, X-ray, and specific wavelengths of ultraviolet radiation are absorbed by certain gases in the atmosphere. The absorbed radiation is then converted into heat energy. Temperatures in this layer can get as high as 1300-1800 degrees Celsius.