airglow

The light produced and emitted by the Earth's own atmosphere, excluding thermal radiation, aurorae, lightning and meteor trains. The spectrum of the airglow ranges from 100 nanometres to 22.5 micrometres. A major component is an emission line due to oxygen at 558 nanometres, which originates in a layer 30 to 40 kilometres thick at a typical height of 100 kilometres (60 miles). From space, the airglow appears as a ring of greenish light around the Earth.