exosphere; outer atmosphere
Scientific term for the outermost layer of Earth's atmosphere, where particles can escape into space. Used in astronomy and earth science contexts.
The exosphere is the outermost layer of the atmosphere.
Artificial satellites fly in the exosphere.
Compound of 外気 (gaiki, 'outer air') + 圏 (ken, 'sphere, zone'). The term is a modern scientific coinage for the exosphere.