NOAA has issued a warning for a possible strong geomagnetic storm: Northern Lights again this evening, October 11th, in Italy?
We are still with our eyes swollen with joy from what we saw on the night between 10 and 11 October 2024 that there is a new alert for a strong geomagnetic storm. There is a serious possibility that the Northern Lights will appear again at low latitudes (and therefore also in Italy). We asked the opinion of INAF’s solar astrophysicist. Here are his words: “Latest NOAA bulletin from a few minutes ago. A geomagnetic storm warning with K-index of 7 or more remains until 8pm tonight. Until two hours ago we were in a G4 and an hour ago in a G3.“
For updates we recommend Doctor Sasso’s telegram channel:
How the Northern Lights phenomenon is created
The aurora, called aurora borealis or australis depending on whether it occurs in the northern or southern hemisphere of the Earth respectively, is an optical phenomenon of the Earth’s atmosphere. Although auroras are seen at night, they are actually caused by the . Our star sends us something else beyond heat and light: it ‘shoots’ the solar wind at us, a flow of electrically charged particles which, when they encounter the Earth’s magnetic field, interact with it. The denser and more intense the solar wind flow is, the more conspicuous the interaction will be, with a passage of energy entering the atmosphere and exciting the oxygen and nitrogen atoms, the constituent gases of the Earth’s atmosphere. This excitation of atmospheric gases causes the play of green, red and blue lights that we call aurora.
The red color of the aurora in Italy (and not green)
As we explained in a previous article, the Northern Lights form after solar particles interact with oxygen atoms trapped in the Earth’s magnetic field. The green color we generally see is due to the (low) altitude. Generally, in fact, they are spotted between 100 and 300 km above our heads. But when solar activity is particularly intense, particles coming from the Sun can interact with molecular oxygen even higher up, between 400 and 800 km. This causes the red color that we also saw in Italy.
