The Sun emitted the most energetic flare of this solar cycle (the 25th recorded, started in 2019) yesterday October 3, 2024 at hours 2.18pm Italian, from the active region AR 3842which will bring “strong” geomagnetic storms to Earth over the weekend with the possibility of observing the Northern Lights at high latitudes. The blasting or flarethat is, an intense and sudden emission of high-energy electromagnetic radiation, was of classthat is, the most intense on the official scale with which these phenomena are classified (A, B, C, M and X). In particular, it was a flare classified as X9.0where the number is an index of the energy emitted by the flare within his class. The flare occurred just two days after another flare very intense, a X7.1 emitted by our star on October 1st. To find a more intense flare we have to go back to the September 2017when a was recorded flare X11.8 and an X13.3 flare. It is therefore a very violent eruption, more so than that associated with the Northern Lights spotted in May.
The flare caused a strong radio blackout (category R3) particularly in the southern hemisphere, but Attention: this, however, does not automatically translate into the fact that here on Earth we will have a geomagnetic storm more intense than that of May 10, nor that we could see splendid Northern Lights here in Italy in the next few days. In fact, let us remember that a flare is an emission of electromagnetic radiation, while to have geomagnetic storms and auroras you also need a violent emission of plasma from the surface of the Sun, and that that plasma must arrive on Earth respecting particular conditions.
In any case, the two recent flares have been associated with the same number coronal mass ejectionswhich according to forecasts by NOAA’s Space Weather Prediction Center are heading towards our planet and could cause category G3 geomagnetic storms (therefore “strong” according to the official classification) between now October 4 and Sunday October 6. According to forecast models, these two coronal ejections occurred at such a distance that they will not be able to merge to give rise to a so-called “cannibal storm”, which would have amplified the intensity of the event.
What should we expect, then? Beyond the catastrophic headlines we are reading in these hours, among the possible effects of a G3 category geomagnetic storm there are:
- malfunctions of electric grills;
- disturbances in the orbits of artificial satellites;
- problems with radio and GPS communications, especially at polar or subpolar latitudes;
- polar auroras visible up to latitudes of about 50°;
- possible stable auroral arcs (SARs) at lower latitudes.
So we probably won’t see the Northern Lights in Italy, though SAR sighting cannot be ruled out. In general, between today and Sunday aintense auroral activity at higher latitudes.
