Airglow & Aurora
The airglow and aurora are emission of the atmosphere in the mesosphere and the ionosphere/thermosphere. The following figure is a photograph take from the international space station on the nightside. The bright green emission on the right hand side is the aurora generated by the precipitation of the energetic particles from the Earth's magnetosphere to the ionosphere.
The green layer above the limb of the Earth is the emission of the airglow. Because the emission is weaker than aurora, it can be
seen only on the limb in this photograph. The
high sensitivity imager of ISS-IMAP/VISI can detect this faint emission of the atmopshere anywhere in the Earth's upper atmosphere.
[Image Science and Analysis Laboratory, NASA-Johnson Space Center. "The Gateway to Astronaut Photography of Earth." http://eol.jsc.nasa.gov/ : ISS029-E-6093]