Friday, May 24, 2024

The Great Aurora Storm of May 10-11, 2024

Best Auroras in decades! Amazing! When charged particles from the sun (and rarely other sources) encounter the Earth, our protective magnetic field diverts and traps them, eventually funneling them into the upper atmosphere near the planet's poles. At least, that is the simplified normal story. Friday night almost the entire planet could view auroras -the system overloaded! This was the view from Emigrant Gap Scenic Overlook on Interstate 80 Westbound in California (taken with my far-from-top-end cell phone) - this is about what it looked like to the naked eye:
With a bit more dark adaptation, and a better camera (still nothing fancy) on a tripod, it filled the sky! I am still constructing a whole-sky image from individual frames, but this is a single 18mm lens frame on a DSLR
It was clearly visible through city light and household lights in the suburbs east of Sacramento, California:
The Aurora was also visible from Namibia in Africa, The Grand Canyon, and The South Pacific! This movie was captured from the website showing the last 24 hours of auroras on May 11th (PDT) sweeping around the planet's North pole:

There is a lot of information here!

Each frame has the HPI (Hemispheric Power Input) in the upper right along with the lead time (most are forecasts for about 30 minutes in the future). Notice that the normally encountered range of powers are 5 to 200 Gigawatts (GW). For comparison, the California ISO normally peaks in late Summer with the entire grid of California requiring about 50 GW of power. Much of this video is over the top or in excess of the 200GW power number. This is a lot of power!

In the upper left corner is the time of the prediction in Universal Time (UTC). California during Daylight Savings (now) is 7 hours earlier than the UTC time (UTC - 7 hours = Pacific Daylight Time).

The unusual electrical activity in the upper atmosphere also created voltages on the ground - there is a fantastic map here produced by the USGS nd NOAA. Not everything in the photos I took appears to be an aurora, however! Some of it appears to be STEVE, a supersonic flow of superheated air in the thin upper atmosphere - the emissions are thermal, not driven by ion impact! There is a broad red band across the center of the image, looking roughly due west, with the moon in the center (the bright white thing in the center).

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