Aurora Alert for Wednesday Night!

Aurora borealis August 26, 2015, over Moray Firth in Scotland

On August 26th, Alan Tough caught this auroral display over Moray Firth in Scotland. The highest-altitude streaks are purple and red. They turn green in the denser zone of the upper atmosphere where they come to a halt.
Alan Tough / Online Photo Gallery

Keep watch on your northern sky after dark tonight (Wednesday October 7th). The aurora borealis could sweep down into our view from its usual far northern latitudes.

For the last 24 hours a geomagnetic storm has been building. It reached a geomagnetic K-index of 7, meaning strong, by 4 p.m. Eastern Standard Time (19h UT). According to an alert from NOAA's Space Weather Prediction Center, "aurora may be seen as low as Pennsylvania to Iowa to Oregon."

Maybe. Aurorae have quite the habit of outwitting space-weather predictors. But occasionally they come even farther south than predicted.

The alert also warns of possible power-system voltage irregularities, intermittent problems with GPS reception, and loss of shortwave radio communication.

It doesn't take a solar flare or even a coronal mass ejection to disturb Earth's magnetic field and allow extra solar electrons to stream into the uppermost atmosphere. A coronal hole in the Sun's outer atmosphere is pointing our way, sending us extra-high-speed solar wind. In the transition zone between normal and fast solar wind, notes Tony Phillips of, "solar-wind plasma piles up, producing density gradients and shock waves that do a good job of sparking auroras."

No promises. . . but don't wake up tomorrow to news of the sight you missed!


2 thoughts on “Aurora Alert for Wednesday Night!

  1. Steven-Leech

    No sign of the aurora yet here in New Jersey, but there’s a second magnitude point source about 3 degrees southeast of Beta Cephei. As far as I can tell, it hasn’t moved (relative to Beta Cephei) for the last hour.

  2. Steven-Leech

    My fault. The object is Alpha Cephei. However, I estimate its magnitude at 2.0 (Polaris is a good comparision), which is brighter than its published magnitude of 2.44. Alpha Cephei is a short period variable, but this is several times greater than its published variability.

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