Astronomy Picture of the Day . ... 6.09.2006 . ... On a quiet night toward the northern horizon over Lake Superior was a long lasting diffuse green aurora . ... Resultant energetic particles such as electrons and protons rain down near the Earth's poles and impact the air. The impacted air molecules temporarily lose electrons, and when oxygen molecules among them reacquire these electrons, they emit green light. ... Publications with keywords: aurora . Publications with words: aurora . ...