Stig Östlund

tisdag, maj 02, 2017

RARE BLUE AURORAS


Northern Lights are usually green, and sometimes red. Those are the colors  produced by oxygen when it is excited by electrons raining down from space. On April 22nd, Didier Lindsey of Fox, Alaska, witnessed an apparition of aurora-blue.

In auroras, blue is a sign of nitrogen (more: www.atoptics.co.uk/highsky/auror3.htm).

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