Auroras are still glowing red @ Utsjoki, Finnish Lapland
© Rayann Elzein
Taken on October 17, 2020 @ Utsjoki, Finnish Lapland
Spoiler alert: We do not know the answer to this question. Where did all the red auroras come from? For much of mid-October, Earth's magnetic field has been very quiet. Extremely quiet. There should have been no auroras at all, yet around the Arctic Circle, photographers recorded scenes like this.

Photographer Rayann Elzein of Utsjoki, Finland, took the picture on Oct. 17th. "I photographed similar displays on Oct. 12th, 13th, 14th, and 15th," says Elzein. "On each occasion, geomagnetic activity was very low (with K-indices no greater than 0 or 1)."

Red auroras appear when particles from space strike oxygen atoms near the top of Earth's atmosphere. However, as Les Cowley explains, the very slow atomic transitions which produce red photons in the aurora zone are easily interrupted. Even experienced observers rarely see them.

Elzein has been chasing auroras in Finland for 10 years. He prides himself on going out in all conditions--even when geomagnetic activity is nominally low. "I can't recall ever seeing so much red on top of the green layer before," he says.

In Tromsø, Norway, aurora tour guide Markus Varik had a similar experience. "Activity was extremely low on Oct. 17th when pink and red colors appeared. After years of guiding, I have never seen anything similar to this."

auroras @ Tromsø Norway
© Markus Varik
Taken on October 17, 2020 @ Tromsø Norway
"It appeared white to the naked eye, but on the camera it was vivid pink," says Varik.

The common denominator seems to be ... quiet. "It seems that the red was most apparent during the lowest geomagnetic activity--that is, when Bz was positive and the solar wind speed was slow (at or below 300 km/s)," notes Elzein. "The solar wind was also dense, with proton densities above 15 p/cm3."

It's a mystery. Aurora experts with bright (red) ideas may submit their explanations here.