2009 February 1
Explanation: Higher than highest communications tower, higher than highest mountain, higher than highest airplane, lies the realm of the aurora. Aurorae rarely reach below 60 kilometres, and can range up to 1000 kilometres. Aurora light results from energetic electrons and protons striking molecules in the Earth's atmosphere. Frequently, when viewed from space, a complete aurora will appear as a circle around one of the Earth's magnetic poles. This particularly rare purple auroral corona occurred in 2004 high above Harstad, Norway.
Authors & editors:
Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply.
A service of: ASD at NASA / GSFC
& Michigan Tech. U.