Strong Geomagnetic Storm Hits Tonight Sept. 7-8

A band of soft rays lit up the northern sky around moonrise tonight. Credit: Bob King
A brief but striking coronal auroral appeared near the zenith around 8:45 p.m. The bright star is Vega in Lyra. There was a lot activity early. From 9-10 p.m.,  the northern sky shows a pasty glow that could easily erupt again into rays and a corona. Credit: Bob King

The big aurora blast we were waiting for appears to have fizzled with only a minor spike in activity. But the sun has more in store. Wednesday’s giant X9.3 flare in sunspot group 2673 sparked a coronal mass ejection (CME) that’s arrived sooner than expected. It slammed Earth’s magnetosphere around 6 p.m. (Central time) this evening and immediately started making beautiful mischief.

This is the aurora forecast oval for 7:15 p.m. Central time this evening (September 7th). This looks good for aurora for us if it keeps up. If you live near or under the oval’s edge, be sure to go outside for a look tonight. Click the graphic to see the latest oval. Credit: NASA / NOAA

The Kp index shot up to “8” at 7 p.m. CDT and is still pinned there as of 10 p.m., making this a G4 SEVERE STORM. The Bz, a measure of the direction of the particle cloud’s magnetic field, stood at —28 at 6:30 p.m. This indicates a steep, southward tilt, the ideal direction for the swarms of electrons and protons to link up with Earth’s field and whip up auroras.

Wow! One of the biggest flares in many years, an X9.3, erupted in region 2673 at 7:02 a.m. CDT September 6. This photo shows the blast in far ultraviolet light taken by NASA’s Solar Dynamics Explorer. A CME launched by the flare has already arrived at Earth and currently spawning auroras. Credit: NASA / SDO

The first auroral fingers dappled the northern sky even in twilight as seen from Duluth, Minn. Between 8:30 and 9 p.m., rays reached to the zenith in a brief coronal display. Hopefully, activity will continue throughout the night though the moon will become more of a bother. Please let us know if you see the aurora via the comments link or just send me an e-mail at:

The aurora forecast was for a moderate G2 geomagnetic storm over U.S. time zones starting at nightfall, but as of 10 p.m. CDT, it’s still rated as a G4 storm. More moderate to strong storms are expected both Friday and Saturday nights.

Hang on, we’re gonna surf this solar wind for a while!

11 Responses

  1. Bill

    Hi there Bob

    Whoa, the KP index is off the chart that I have not seen for a long long time. Only problem I see with the whole thing is clouds..

    Am curious as if anyone is seeing anything and if the clouds have started to clear out yet??


    1. astrobob

      Hi Bill,
      Clouds clearing out in Duluth. Just saw the bird-like corona aurora overhead. Rays in the north. This thing’s big.

  2. Leslie

    Hi Astro Bob with all these crazy things going on.. you hear people talking about a astrological and planetary alignment causing destruction on September 23. Have you heard anything about it? Is There anything significant on that day ?

    1. astrobob

      No, haven’t heard but I’m not surprised. Someone’s always saying destruction’s near because of alignments, etc. It never comes true. Just preying on people’s fears.

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