Brief Aurora Weds. Aug. 20-21 – Maybe More Overnight?

A low arc and dim green rays were topped by a red border in this photo taken around 11 p.m. CDT Wednesday night Aug. 20. Details: ISO 3200, f/2.8, 20mm lens. Credit: Bob King

Scandinavians were the lucky ones yesterday when auroras broke out during their nighttime. Here in the U.S. it was still afternoon. Auroras are mighty scarce in sunshine.

Tonight to my surprise, we had a brief display around 11 p.m. CDT.  An arc rose above Boulder Lake north of Duluth, Minn., where a group of naturalists and I spent the night at the telescope under a starry sky. At the sight of a few needle-thin rays, one in our group jumped in a canoe and paddled out into the lake for a better view.

More rays taken a few minutes after the first photo. The display was fairly quiet and reached to about 10 degrees above the northern horizon. Credit: Bob King

Not 15 minutes after it began, the arc and rays faded away, leaving only a faint, diffuse glow until fog settled in around midnight. The Kp index rose slightly during the evening, and the ACE satellite plot has shown a southward pointing Bz or solar magnetic field in Earth’s vicinity for many hours. This is often a good indicator of auroral activity on the way.

The show was subtle but no one was disappointed. Auroras are always welcome around here.

2 Responses

  1. Bruce Brovold

    Roman goddess of dawn: in Roman mythology, the goddess of the dawn.
    I had to look up Aurora, as I did not know what it meant.

    I have not see a spectacular Aurora since back in the 70’s when I was on a camping trip in northern Minnesota. That one was awesome, it seemed like the whole sky was on fire. The whole spectrum of colors were brilliantly spread across the northern sky.

    1. astrobob

      Hi Bruce,
      Auroras come in so many varieties. Having lived in northern Minn. for many years, I’ve seen little displays like last night’s up to much rarer all-sky variety like yours. We’ve had two excellent auroras here this year – one back in May, the other in July.

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