A geomagnetic storm possibly of category G3i.e. “strong” according to the official classification, could affect the Earth between today and tomorrow in the form of a so-called “cannibal storm”. Despite the term “strong”, there are no risks of blackouts or other major inconveniences, while the possibility of sighting remains uncertain Northern Lights from Italy. The forecast comes from NOAA’s Space Weather Prediction Center, based on two coronal mass ejections (CME, Coronal Mass Ejection) departed from the outermost part of the Sun’s atmosphere on November 9th and 10th. The exact timing of the arrival of these two streams of solar plasma is not yet clear, so there is a fair amount of uncertainty about the overall effects of the arrival of these two CMEs.
At the moment NOAA forecast models indicate the possibility of two coronal ejections they merge just before reaching Earthbecause the second, although starting later, moves more rapidly: in this case we speak of a “cannibal storm” due to the fact that one CME “engulfs” the other. When this happens, the “force” of the two coronal ejections hits the Earth together and a more intense geomagnetic storm can occur as a result. In this case, even if there is still no certainty whether the merger of the two CMEs will actually take place, at the moment this is considered the most probable scenario, with the possibility that the combined effect of the possible “cannibal storm” is that of a category G3 geomagnetic storm (the maximum category is G5), i.e. a disturbance of the Earth’s magnetic field capable of creating orientation difficulties for artificial satellites, temporary interruptions in radio communications and the Northern Lights visible up to latitudes of approximately 50°.
In this specific case, theKp index – which measures the disturbances in the Earth’s magnetic field caused by solar activity – could reach a value of tomorrow 7sufficient in principle (but there is no guarantee) to be able to faintly spot red aurora borealis or other auroral phenomena such as HRH (Stable Auroral Red arc) also at the latitudes of Northern Italy, although probably visible only through the webcams of the Alpine refuges.
The “cannibalistic” storms they are not rare in periods of maximum magnetic activity of the Sunwhich in this period is right at the peak of its eleven-year cycle of activity. The last time it happened in April last year, causing a “severe” disturbance of the Earth’s magnetism (category G4). In any case there is nothing to worry about and we remember that every prediction in the field of space weather must always be taken with the necessary uncertainties, which in this case are still significant.
