On the evening of November 5, 2023 I was lucky enough to witness a truly rare show: we’re talking about a northern lights display visible from Tarquinia (about 90 km north of Rome).
Astrophysicist Gianluca Masi explains that it probably wasn’t an aurora, but an SAR; here are his words:”
Probably, what was observed on Sunday evening by a good part of the country was not a polar aurora, but another extraordinary celestial phenomenon, still linked to the physics of our wonderful atmosphere: a Stable Auroral Red arc, or SAR for short.
It originated due to the emission of thermal energy in the upper atmosphere from the structure corresponding to the “Earth’s Ring Current”, doughnut-shaped and carrying millions of amperes around our planet.
SARs are a recent discovery (1956) and are almost monochromatic, exactly that red we admired, due to the presence of oxygen, as I described in yesterday’s post.
The fact that they are red, among the most crimson things in the sky, makes SARs hard to catch with the naked eye, due to the retina’s modest sensitivity at those wavelengths. More effective are cameras, which might help us capture them more easily, now that solar activity is getting interesting.
In short, perhaps we were even luckier “.
Ultimately, one could infer that both an aurora and an SAR occurred, but from Italian latitudes the SAR’s red lights prevailed over the aurora’s green ones.
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