A geomagnetic storm of Category G3that is, “strong” according to the official classification, should hit the Earth tomorrow Tuesday, July 30, 2024 according to the forecasts of the Space Weather Prediction Center of NOAA. According to the forecasts it should also be a “cannibal” stormdue to the fusion of two expulsions of matter from the Sun that can therefore reach the Earth with greater force. The news comes in the wake of the misinformation spread last week about the arrival of a possible global radio blackout (which in fact did not happen), and many are already using the words “strong” and “cannibal” to ride the wave of concerns that had been created. In fact, however, there is nothing to worry about: a “cannibal” storm of category G3 hit the Earth also in December and we are still here to tell the story. A “strong” storm can in fact create some malfunctions in the electrical grids, orientation problems for satellites, possible intermittencies in radio and satellite communications and aurora borealis at latitudes above 50°, therefore not visible from Italy as instead happened in May with a G5 storm, or stable auroral arcs like those spotted in Italy in November 2023.
What’s Happening: The Origin of the Geomagnetic Storm and Predictions
Between July 27th and 28th the Sun has been affected by a series of solar flares from the sunspot complex AR3765-67Solar flares, or solar flaresare sudden releases of energy accumulated by the magnetic field of our star in the form of high-energy electromagnetic radiation. The flares of the past few days were not particularly intense, but the release of energy has managed to cause several plasma eruptions from the outermost part of the solar atmosphere, in technical jargon CME (Coronal Mass Ejection“coronal mass ejections”). According to NOAA, there could be 4 or 5 CMEs in total.
These ejections travel at different speeds, and it can happen that a CME can reach a previous one, “cannibalizing” it and forming a single plasma flow high energy directed towards the Earth. In this case we speak of “cannibal” storm and the effect on Earth is to increase the disturbance in the Earth’s magnetic field, or the intensity of the resulting geomagnetic storm. Forecasts say that the first two CMEs emitted on July 27 have merged and will reach our planet tomorrow July 30thcausing a geomagnetic storm of Category G3.
But there is more. The CMEs that follow the first two are meanwhile traveling in the “vacuum” created by the latter, a bit like a car that “follows the slipstream” of a truck on the highway. Encountering less resistance, these CMEs can be expected to arrive on Earth less “slowed down” the following day, i.e. Wednesday, July 31stpossibly increasing the effects of the “tail” of the geomagnetic storm caused by the cannibal CME. At the moment the Space Weather Prediction Center predicts for the July 31st the possibility of a geomagnetic storm of Category G2that is, “moderate”.
Possible Geomagnetic Effects: What to Expect
Given that those of NOAA are forecasts only and there is no certainty that things will actually go this way, these are the possible effects of a geomagnetic storm of Category G3 as expected for the July 30th:
- possible malfunctions of the electric grids;
- possible disturbances of 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 at lower latitudes.
As for a geomagnetic storm of Category G2 like the one waiting for the July 31stpossible effects include:
- possible malfunctions of electrical grids at high latitudes;
- possible orientation problems for artificial satellites;
- possible weakening of high frequency radio signals;
- Polar auroras possible up to latitudes of about 55°.
In any case, geomagnetic storms they do not cause effects on humans or on animals, so they are to be categorically excluded health risks.
