Airglow

The night sky light or night sky lights (English airglow ) denotes a faint glow higher layers of the atmosphere. It was discovered in 1868 by Anders Ångström.

The residual brightness of a moonless night sky not only the result of artificial light sources on the ground, the indirect scattering of sunlight and the light of the stars, but also from processes in the ionosphere. The gas atoms and molecules (especially oxygen and nitrogen) in the layer to be ionized and dissociated by solar ultraviolet radiation. In the recombination of the particles of radiation emitted in the visible range, which still persists long after sunset.

That through this process resulting in day light is much more intense than the night, but is outshone by the sun's light. From outside the Earth's atmosphere, the airglow appears as luminous rings at a height of about 90-500 km above the ground surface, especially a green band dominates in 90 to 100 km altitude. Because density changes due to gravity waves can be observed in this form of individual bands.

Terrestrial telescopes are affected in the wavelength range of visible light by airglow, which is why space telescopes such as the Hubble telescope are significantly more sensitive here.

The 23 September 2009 into space shot SwissCube to investigate the phenomenon airglow.