What Is the Composition of the Thermosphere?

The thermosphere consists primarily of oxygen, nitrogen and a helium. This layer of the Earth’s atmosphere lies below the exosphere and above the mesosphere, between 56 and 621 miles above the surface of the Earth.

Gases below the thermosphere contain different types of molecules and atoms which are bound and mixed together by turbulence. However, frequent collisions are not common in the thermosphere as gases in this region are broken apart by X-ray and ultraviolet photons from the sun. These high-energy photons strip gas particles of their electrons, which creates an electrically-charged region of molecules and atoms.

The thermosphere absorbs the bulk of UV and X-ray radiation from the sun, which cause temperatures to rise. Temperatures in the thermosphere vary based on location within the region and the sun’s activity levels. Temperatures increase sharply in the lower portion of the thermosphere, then flatten and remain steady in the middle and upper regions. The thermosphere is roughly 360 degrees Fahrenheit hotter during the day than at night. Temperatures in the upper region range from 930 degrees Fahrenheit to more than 3,600 degrees.

Because the thermosphere is located in the upper atmosphere, the atmospheric pressure of the thermosphere is minuscule relative to that of the Earth’s surface.