Nov. 6, 2022:
It could happen again–and soon. Twenty-one years ago, a full-halo CME struck Earth’s magnetic field, sparking a severe G4-class geomagnetic storm. “Skies over Central Europe glowed bright red and violet,” recalls Heiko Ulbricht, who photographed the display from Saxony, Germany, on Nov. 6, 2001:
“The shock front hit the Earth’s magnetic field around 2 a.m. CET–good timing for sky watchers in Europe,” says Ulbricht. From there, auroras spread around the world, descending as far south as Florida, Texas, and California in the United States. The storm persisted for more than 24 hours.
The CME left the sun two days earlier, propelled by an X1-class solar flare from sunspot AR9684. SOHO coronagraph images of the CME were quickly overwhelmed by a “snowstorm” of energetic particles accelerated by shock waves in the approaching storm cloud:
The kind of explosion that produced this storm is, interestingly, not rare. Young Solar Cycle 25 has already produced 8 similar X-flares since 2021. None of the related CMEs delivered a direct hit, however.
“If you look at the sun today, it could definitely produce a spectacle of this kind again,” says Ulbricht. Browse the aurora gallery from 21 years ago to see what might be coming.
Nov. 6, 2001, Aurora Photo Gallery
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November 7, 2022
21 years Ago, A Severe Geomagnetic Storm | Spaceweather.com (spaceweatherarchive.com)
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