A category G3 geomagnetic stormthat is to say “strong” according to the official classification – which goes from G1 and G5 – could affect the Earth today, December 9. As reported by NOAA’s Space Weather (National Oceanic and Atmospheric Administration), it was caused by acoronal mass ejection (CME) towards Earth, which occurred last December 6 and is associated with a solar flare of class M8 – of moderate intensity – started from sunspot 4299.
In reality, despite being classified as “strong”, this event It shouldn’t cause any particular inconvenience. At the time of writing, the geomagnetic storm has not yet reached our planet: according to NOAA forecasts, disturbance of the Earth’s magnetic field could occur starting from late Italian afternoon.
On this occasion, however, it will be rather difficult to observe any Northern Lights also from Italy. Predictions, however, are particularly difficult to make and it is not certain that they will prove correct: we will have to wait and see if we are lucky!
What NOAA forecasts reveal and the possible risks of the geomagnetic storm
On December 6th sunspot 4299 produced a medium intensity solar flare – class M8–, i.e. a sudden release of energy (which was previously stored in the magnetic field of the Sun) in the form of energetic electromagnetic radiation, also visible in the image below.
Based on all this data, NOAA issued a warning for class G3 geomagnetic storm expected on December 9th, in the late Italian afternoon: the geomagnetic response will however depend on the intensity and orientation of the magnetic field.
From the point of view of possible risksthe geomagnetic storm will not cause particular consequences: according to NOAA they could occur limited and temporary effects, as possible satellite navigation and low frequency radio navigation problems, with minor effects on other technological infrastructures. In particular, according to the bulletin released by the US agency, the possibility of minor or moderate blackouts (category R1 and R2) is equal to 65%, while the possibility of intense blackouts (R3-R5) is just 15%. In short, there is nothing to worry about.
Will it be possible to see the Northern Lights in the skies of Italy?
But, therefore, during this geomagnetic storm it will be possible to see some Northern Lights also from Italyas happened last November?
First of all, it must be said that the disturbance of the Earth’s magnetic field it is measured with a parameter called Kp index – which ranges from 0 to 9 – and measures the disturbances in the Earth’s magnetic field caused by solar activity. The geomagnetic storms of recent years have demonstrated that, at our latitudes, it is possible to observe gods auroral phenomena (such as red auroras or auroral arcs) with a Kp index of 7.
In the case of today’s geomagnetic storm, forecasts indicate a maximum of Kp 7-so it will be rather difficult to observe the Northern Lights even from Italy, as this is a limit value.
Another value to consider for Northern Lights forecasts is the Bz index, which indicates the direction of the interplanetary magnetic field. If this value is positivemeans that the magnetic field repels the particles expelled by the Sun; if it is negativeindicates that the magnetic field allows the particles from falling back into our atmosphereincreasing the chance of seeing strong Northern Lights. Simplifying, it is as if the negative Bz index represented a “open door” for the entry of particles from the Sun into our magnetic field. In the case of this G3 storm, the Bz index is predicted to reach peaks of –3.71.
Be careful though, it doesn’t mean that NOAA’s predictions will turn out to be correct: therefore, the possibility of observing the Northern Lights also remains open at our latitudes.
