October 9, 2013 Auroras
Grand Rapids, MN
Another CME was headed for Earth after a filament erupted near the eastern limb of the sun. Just like the week before, the CME arrived at Earth a full day ahead of schedule. The CME had looked pretty weak on SOHO animations, but the impact was surprisingly strong, sending Bt up to around 30 nT and Bz dropping into the negative mid teens. I planned to start shooting when it got dark, but I had a mentoring event in the early evening (before it got completely dark). Right after the event, I took my mentee up to the north side of town to point out the auroras, and they were already in a band nice and high in the sky. I dropped him off at home then raced back to my house to get the cameras, but the band of auroras had disappeared in just a few minutes, and Bz had gone north. The rest of the show would be a rather mellow one on the northern horizon. I had a lot of images to process from the October 2 event, so I took care of the processing while waiting for Bz to drop back south. It never did, but I went out anyway and snapped a few images of the more mellow, after-dark show.
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| Auroras on the northern horizon well after Bz had gone north. |
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Solar wind data for this event from the ACE spacecraft. |