Definition, Meaning & Synonyms

exosphere

noun
ˌɛk.səˈsfɪr
Definition
The outermost layer of the Earth’s atmosphere, extending from the thermosphere and transitioning into outer space.
Examples
  • The International Space Station orbits within the exosphere.
  • Satellites operate in the exosphere, where there are very few air molecules.
  • Spacecraft must be designed to withstand the harsh conditions of the exosphere.
Meaning
The exosphere is where the atmosphere thins out and eventually fades into the vacuum of space. It is characterized by very low density and temperature, and is primarily composed of hydrogen and helium.
Synonyms
  • outer atmosphere
  • upper atmosphere