Spaceweather.com reports on the misnamed proton arcs:
Aurora photographers see these structures from time to time–tight ribbons of light, sometimes red, sometimes green, writhing across the night sky. They are commonly called “proton arcs.”
Yet aurora scientists say they probably have nothing to do with protons.
“My opinion, and I believe the consensus of most aurora scientists, is that these arcs are not proton related, ” says Jason Ahrns, a researcher at the University of Alaska Fairbanks, “but I don’t know what does cause them.”
From Spaceweather.com’s gallery:
