October 7, 2024 Auroras

Lake Winnibigoshish

Wow, what an incredible display! After a weekend anticipating great auroras from a strong, Earth-directed CME after an X-class flare, the CME impact was a bit of a dud (see the graph at the bottom of this page). It had been expected to arrive on Saturday, but it arrived very early Sunday monring and was initially not as impactful as it was anticipated to be. Bz was mostly positive, and speeds were around 500 km/s. Late in the day on Sunday, Bz turned negative to about -10 nT, and the skies were clear with no moon, so I decided this would be a good night to go to Lake Winnie. I hadn't been there in about a year, and tonight, the conditions were prime for shooting there. The wind was light, and I expected the auroras to be relatively low on the horizon. I drove out to the Forest Service boat landing, where I immediately saw the auroral arc.

The auroral arc when I first arrived.

I was only there for about 20 minutes before a substorm began to build. It came on rather slowly, but this allowed the auroras to be relatively slow moving, and I could use some longer exposures to gather more light. I was at ISO 1600, f2.8 and 25 seconds, but I changed that to ISO 3200 and 8 seconds to make sure the auroras weren't blurred. They were brighter but not super bright. What was really interesting was the unique structure in the taller columns. With my eye, I could see that they were brightest at their base then slowly faded like they usually do, but then near the very top, they got brighter again. This was something I hadn't seen before. The camera revealed that these brigher tops were a very intense, very pure red. I had never photographed that intense a red before this. Just looking at those reds on my computer screen as I type this up has me mesmerized.

A substorm starts with some intense reds.

Wow, that is really red!

The reds faded out, but the substorm continued. It kept going for about an hour. At some point during this, another vehicle came up to the boat landing. I sometimes wonder what they'll be up to when they arrive. Some people like to come to the boat landings and just sit in their vehicle, and some actually come for the northern lights. This time, two women hopped out with their phones and started taking pictures, but they couldn't get the flash to turn off, so I showed them how to turn off the flash and do a long time exposure with an iPhone. They were happy about that. Then, they started talking about how they saw someone last year who was out taking a bunch of pictures. I told them I didn't remember talking to them, but I did remember the husband/wife owners of the Big Fish Supper Club. One of them said, "Yeah, we own the Big Fish, My husband and I were the ones who talked to you last year."

I said, "Yeah, okay, then I definitely remember you!" Seems like they had just gotten off work and were enjoying a couple beers when they heard abou the auroras and decided to have a look.

The reds calm down, but the display brightens.

Here it is at its fullest extent, looking northwest.

Here it is at its fullest extent, looking northeast.

The storm eventually quieted down, and the auroras retreated. I had arrived and seen an early show, and if I had left at this point, I would have had a full night's sleep, but then I saw the auroral arc reform back to its pre-substorm shape. That had me thinking it wouldn't be too long before the next substorm, so I decided to stick around for it.

The auroral arc refocuses.

Well, it turned out I would wait for two hours. I would have been in bed by 11:30, but now, here I was, still at the boat landing, the time was nearly 1:00 AM, and the substorm was only now getting started. It came on even more gradually than the first one, but it was rather interesting because Bz had not been strongly south (-10 nT or lower) since about 6:30 PM. It was still fluctuating quite a bit between -7 and about +4 nT, and speeds were around 450 km/s.

Color starts to develop to the northwest at 12:50 AM.

The second substorm.

One of the last shots I took this evening.

One of the last shots I took this evening. Looking northeast at the contrasting dark sky and auroras.

My last shots were taken at 1:46 AM, about three hours later than I had originally planned to leave. I would get home after 2:30. I'd be pretty light on sleep, but this was a worthwhile shooting session.

Shot with my 24mm lens on the 5D Mk III.

Shot with my 24mm lens on the 5D Mk III at the brightest red moment.

There's some structure and color here.

Some finer structure.

Some finer structure, looking more directly out at the water.

Solar wind for the three days October 7-9.

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