Manuel retweetledi

Just a few days ago was the 105th anniversary of the 15 May 1921 Great Geomagnetic Storm. The storm produced overhead aurora and corona as far south as Tucson, Arizona. That's as far south as northern Florida, central Italy and central Spain. Aurora was visually spotted at the Apia Observatory, Samoa at a geomagnetic latitude of only 16°! The storm reached an estimated minimum DST index of -907 ± 132 nT - a Carrington-level event. Compare that with the DSTmin = -406 nT during the 10-11 May 2024 G5 Gannon storm.

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