It wasn't quite the northern lights: what Ukrainians really saw in the sky

Recently, a strong geomagnetic storm caused a spectacular light show in the sky, including in regions that are not characterized by the aurora borealis, including Ukraine. But experts say that the flashes were not actually Aurora, but a related phenomenon.

According to IFL Science, it is about SAR and STEVE. Scientists explained what these phenomena are and what the aurorae have to do with them.

SAR stands for Stable Auroral Red arcs, i.e. stable red polar arcs. But this name is only partially accurate. The light arcs in the sky are indeed red, but they are not always stable and do not come from the aurora borealis.

Mankind has been observing SARs since the time it managed to settle in higher latitudes. They were first described scientifically in 1956, and the name was coined at the same time. Since then, researchers have been able to clarify that real auroras are associated with charged particles entering the Earth's atmosphere from space, while SAR involves heating of the upper atmosphere from below.

Both phenomena can also be confused because of certain external similarities. But the fact that they can both be observed during geomagnetic storms also contributes to the confusion. They occur when bursts of solar activity lead to the bombardment of the Earth's atmosphere with charged particles.

However, the Aurora is caused by particles that directly affect the atmosphere, and its color depends on what gases they collide with. And SAR is based on a more complex mechanism. Due to a geomagnetic storm, a lot of energy is released into the Earth's ring current system. And these currents carry an electric charge around the planet. Because of this "overload," part of the current flows into the upper atmosphere and creates a red light phenomenon that looks like the aurora borealis. In photos taken with modern cameras, both Aurora and SAR look brighter than in real life.

The latter phenomenon, by the way, combines purple, green, white, and red colors, although white dominates. STEVE looks more like a narrow, winding streak across the sky than a large canvas. It is not always visible, but it is usually possible to see it when a green glow is visible lower in the sky in the form of a "particle" from electrons arriving from space.

Earlier, OBOZ.UA reported that during the flashes in the sky on November 5, an increase in the radiation background was recorded in Ukraine.

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