The (rare) spectacle of the northern lights over Cortina and the Dolomites

by archynewsy
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This is not an unusual occurrence, but it is not a phenomenon that occurs very often in Italy either. On Sunday night, shortly after sunset, the sky over Cortina and the Dolomites was illuminated by an aurora borealis. Numerous videos and photos documenting this rare astronomical phenomenon in the southern Alps have already appeared on social media.

The aurora has been seen throughout Europe: from Poland to Slovenia. This aurora was caused by a solar storm of category G3, (maximum G5)so strong that within the Arctic Circle the aurora was seen even during the day, when there is sunlight, which only happens once every ten years.

In the next few hours, the aurora will also be visible over North America. The spectacular aurora was also seen in France and in Italiaeven over the Po delta.

Polar auroras (borealis and austral) are produced by the interaction with the Earth’s magnetic field of the flow of charged particles emitted by the Sun in cycles of maximum and minimum activity that last about 11 years. Since the end of 2019, our star has entered cycle 25 (calculated from 1755) and is ascending towards the cycle high to be reached in the second half of 2025. The closer the cycle maximum approaches, the more the number of sunspots and associated flares increases.

The spectacle of the polar lights is due not only to their incessant movement across the sky, but also to their colors. The color verde It is produced by the interaction of solar particles with atomic oxygen in the upper atmosphere at an altitude of about 100-160 kilometers, the color blue violet by nitrogen atoms about 90-100 kilometers above the surface. The color rojo It only manifests itself in very intense solar storms that also excite molecular oxygen (O2) at altitudes of about 240 kilometers, giving the night sky its typical blood red color.

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