Cannibal solar storm arriving on Earth with possible Northern Lights, what can happen

Today December 1, 2023 the Earth will be hit by one geomagnetic storm classified as “forte” (class G3) from the Space Weather Prediction Center (SWPC) of NOAA, the American climate agency. It is a particular storm, defined by NASA “cannibal”: it results in fact from one expulsion of high energy charged particles from the upper atmosphere of Solewhich occurred on November 29, 2023, which will incorporate three solar emissions dating back to November 28th. The merging of these three energetic streams of particles is directed towards us and has led the SWPC to raise the intensity of the solar storm approaching Earth from “moderate” to “strong”. In areas of the planet not illuminated by the Sun they will be seen intense Northern Lights at high latitudes, while at our latitudes, always in the nocturnal areas, they will be able to be spotted red auroras (like those spotted in Italy in September 2023) or stable auroral arches (seen in Italian skies in November 2023).

What is a “cannibalistic” solar storm

The Sun’s magnetic field can accumulate large quantities of energy in certain points which then – as happens with i earthquakes – can free itself all together. This rush of energy causes an intense solar flare (flashes of high-energy radiation) and sometimes a violent expulsion of plasma contained in corona, the highest part of the solar atmosphere. In this case we are talking about coronal mass ejection. If these expulsions reach Earth they can cause solar storms and polar auroras.

In the case of multiple coronal mass ejections, close together in time and directed in the same direction, if the last expulsion is faster than the previous ones it can reach them and merge with them, incorporating them. This is what NASA means by “cannibalistic solar storm”. A storm of this type then becomes more intense but also more complex and therefore more unpredictable, simply because the amount of charged particles arriving on Earth becomes greater. The result is that the corresponding geomagnetic storms that hit Earth (i.e. the disturbance of the terrestrial magnetosphere) they become more violent and prolonged.

Credits: NASA Scientic Visualization Studio.

What consequences and risks can we expect

The solar storm approaching Earth originated from the solar active region called AR 3500where a X-class flare (the most intense). The resulting ejection caught up with the previous ones, resulting from a flare of classe M (the second most intense). In the absence of this “cannibalism” event the solar storm on Earth would have been classy G2or “moderate” according to the official classification of NOAA. After the merger, the resulting disturbance of the Earth’s magnetism will be class-like G3or “strong”.

The conditions are therefore similar to those that occurred on November 5, 2023, when stable auroral arcs were spotted in Italy, initially mistaken for the Northern Lights. Possible effects are:

  • radio and GPS communications problemsespecially at high latitudes;
  • intense polar auroras visible up to unusually low latitudes (about 50°);
  • possible phenomena such as stable auroral arches at lower latitudes.

We do not expect significant risks of severe damage, for which a solar storm class would be required instead G4 (“severe”) or G5 (“extreme”), i.e. more intense than today.

In Italia we should not be able to spot auroras or other phenomena, simply because the storm will hit the Earth while our country is illuminated by the Sun. However, visible lights or glows after sunset cannot be ruled out.

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