Surprise: Some Red Auroras are *not* Auroras

.
.
Observing a recurring feature of the Earth’s ring current system.

Nov. 22, 2021: The biggest geomagnetic storm in years erupted this month when a Cannibal CME slammed into Earth’s magnetic field. Auroras spread as far south as California and New Mexico. Upon closer inspection, however, not all of those lights were auroras. Some were “SARs.”

SARs are pure red arcs of light that ripple across the sky during strong geomagnetic storms. Here’s an example from Finland in 2018:

“The SAR was visible to the naked eye for nearly 30 minutes and, after fading a bit, remained visible to my camera for another hour and a half,” recalls photographer Matti Helin.

On Nov 4, 2021, Earth experienced a veritable SAR storm. “We photographed SARs as far south as the McDonald Observatory in Texas,” reports Jeff Baumgardner of Boston University’s Center for Space Physics. “The bands of light swept over our cameras near Boston, then headed south. We knew something special was…