A Proton Arc over Norway

A Proton Arc over Norway
A  proton arc is a rare type of aurora.
As the name indicates, proton arcs are caused not by electrons but by more massive protons that bombard the Earth's atmosphere following an energetic event on the Sun.

Reference:
http://web.stanford.edu/~mystical/Publications/spasojevic2004_arcPlume.pdf
 
Video source: https://vimeo.com/timoksanen
Video credit: Timo Oksanen

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