Surprise Geomagnetic Storm

Aug. 8, 2022: A solar wind stream hit Earth’s magnetic field on August 7th. At first, the stream’s velocity was low, but during the day it sped up to more than 600 km/s, ultimately triggering a G2-class (moderately strong) geomagnetic storm. This event was not in the forecast, so the resulting auroras came as a surprise.

“I was already in bed getting ready for sleep when the storm began,” says Ruslan Merzlyakov. “Rushing to the beach in Nykøbing Mors, I was able to photograph the first summer auroras in Denmark in 5 years.”

“Seeing the lights dance on a warm summer night was a great experience!” he says.

In North American, auroras spilled across the Canadian border as far south as Pennsylvannia. In Wayne County, PA, Sujay Singh photographed both red auroras and STEVE. Auroras were also sighted in Montana and the Dakotas.

The solar wind stream that sparked this display is a bit of a puzzle. It might be the early arrival of a stream originally expected on Aug. 9th, flowing from an equatorial hole in the sun’s atmosphere. Or, perhaps, a CME was involved. A discontinuity in solar wind data at 0045 UT on Aug. 7th hints at a shock wave embedded in the solar wind. These days, the active sun is producing so many minor explosions, it is easy to overlook faint CMEs heading for Earth.

“Earth’s magnetic field is still reverberating on August 8th,” reports Stuart Green, who recorded the event using a backyard magnetometer in the UK:

Despite the surprise, subscribers to our Space Weather Alert Service were aware of the storm. Instant text alerts announced the arrival of the solar wind and the subsequent G2 event. Aurora alerts: SMS Text

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