Astronomy Image of the Day
Auroral Corona over Norway
14 October 2014
Harald Albrigtsen

NASA Astronomy Image of the Day for 14 October 2014
Higher than the highest mountain lies the realm of the aurora. Auroras rarely reach below 60 kilometers, and can range up to 1000 kilometers. Aurora light results from energetic electrons and protons striking atoms and molecules in the Earth's atmosphere. Somewhat uncommon, an auroral corona appears as a center point for a surrounding display and may occur when an aurora develops directly overhead, or when auroral rays are pointed nearly toward the observer. This picturesque but brief green and purple aurora exhibition occurred last month high above Kval�ya, Troms�, Norway. The Sess�yfjorden fjord runs through the foreground, while numerous stars are visible far in the distance. APOD Wall Calendar: Land and Skyscapes
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Image and explanation courtesy of NASA Astronomy Picture of the Day