Another Major Geomagnetic Storm!

Last May, I posted about what was one of the strongest geomagnetic disturbances in recent decades. On the night of 10-11 October, 2024, it happened again.

We're of course not so far from the autumn equinox, which happened only some three weeks ago. At these times, aurorae have long been understood to display seasonality due to the alignment geometry of Earth's magnetic field with the Sun's field.

We reached a good and prolonged G4 strength, yielding extensive if less structured aurorae on the 10-11. With clear skies once again blessing the UK, pretty much everyone was able to enjoy the display.

How it became rough. Very rough!

I rushed out to the field shack as soon as it was dark enough to see the glowing sky. Large cumulus clouds were starkly silhouetted against the aurora, which extended to at least 40 degrees above the horizon in the early phase.

The little 6m, 3-ele beaming to the NE. Appearance is close to the naked-eye view.

 

 

Early phase of the aurora, with a bit of 6m field shack activity, beaming north.

Up went the telescopic aluminium pole and the 50MHz, 3 element Yagi atop. Though the strongest activity was initially to the north east, the strongest auroral signals were coming from due north. I made a single QSO but didn't persist with calls, because there was a contest on. I don't really do contests, especially when I don't know what the reporting rules are! In any case, the aurora was too fantastic to shout at some obsessive points collector somewhere.

 

I heard one call at reasonable strength from France, but not as many as during May. Northern Ireland, England and Scotland were all putting up participants via aurora.

By magnetic midnight, things took an uptick in activity. Quite vivid reds were persistent at the eastern and western limits, with possible 'STEVE' at times. At 20:59UT, I spotted a bright, regular patch of green appear to the ESE. There are no known ionospheric heater arrays in that direction, but it did seem so rectangular and uniform that it may have been artificially-induced. It also vanished in a couple of minutes. I've never seen anything like it in 50+ years of looking up.

The highly-unusual patch of uniform, apparently rectangular aurora that appeared at 20:59UT, 2024 October 10. It lasted for only a couple of minutes. Looking 108 degrees true from central Anglesey.

The activity continued at a strong level through the whole night and into the next morning. The end of the contest on 6m, coupled to most of them being G4 and therefore getting on in age, led to 6m becoming quiet after about 21UT. 

So bright and extensive was this display that, like May, it was possible to read large print text under its light.

The aurora was extensive and bright enough to light up the surroundings markedly.

Later phase of the display, apparently showing wave structure.