Picture of Airglow, Gegenschein, and the Milky Way

I chose the NASA Astronomy Picture of the Day from April 20^th, 2013. Taken from Las Campanas Observatory in the southern Atacama desert of Chile, this scenic picture is of the Airglow, Gegenschein, and the Milky Way. The green atmospheric airglow covers the thin clouds due to chemiluminescence, which is the production of light in a chemical reaction. The chemical energy is created by the Sun’s extreme ultraviolet radiation and is also found around the globe. Also visible is the Gegenschein, seen as a faint bluish cloud in the picture. A Gegenschein is when sunlight reflects on dust along the solar system’s ecliptic plane. The Milky Way is also present in this picture. One question I have is how often do Airglows and Gegenscheins occur, and are they a common?

http://apod.nasa.gov/apod/ap130420.html

Jillian Jiampietro