Something is happening to our Sun. On July 11, one of the sunspot regions of the atmosphere caught the attention of observatories due to a sudden increase in its ultraviolet and X-ray brightness.
At that time, the phenomenon affected radio amateurs located on both sides of the Pacific Ocean, who saw their transmissions momentarily interrupted.
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It had happened a solar flare. That is, a sudden emission of electromagnetic radiation and energy particles located in a small region of the solar atmosphere. In this region, the magnetic fields are particularly strong and complex.
Often a solar flare precedes a much more impressive event. The same magnetic field that generated the explosion is twisting beneath the Sun’s surface, drawing massive amounts of solar plasma outward and, like a cannon, launching it at high speed into space.
This is a coronal mass ejection. Unlike radiation from an ordinary flare (which hits the Earth at the speed of light, about 8 minutes), coronal mass ejections are made up of particles moving at a certain speed.
This means that they can take anywhere from a few hours to several days to reach Earth orbit.
And that’s what happened. Last week, there were different eruptions of moderate intensity until, on July 15, one of them was accompanied by a spectacular ejection.
Of course, with a particularity: this time, it is aimed at our planet. And we’re looking forward to it Thursday July 21.
The story repeats itself
This is not the first time that we find ourselves in this situation. Although the physics of these phenomena is not fully understood, we are convinced that their nature is primarily magnetic.
And also that its occurrence is not fortuitous: approximately every 11 years our Sun goes through periods of strong magnetic activity (called solar maxima).
During the maxima, the frequency of these events is particularly high. At the moment we are entering the maximum of the current cycle, whose peak of activity should be reached throughout the year 2024.
The range of a coronal mass ejection is often accompanied by striking auroras. However, the effects of greater global range occur when it interacts with the so-called Earth’s magnetosphere: a kind of protective bubble that surrounds the Earth, in which the intensity of the Earth’s magnetic field is able to deflect the charged particles released by the Sun (the solar wind).
This allows, among other things, the Earth to retain its atmosphere.
In contact with an ejection, the magnetosphere compresses and interacts with it by modifying its structure. Earth’s rapidly changing magnetic field produces induced electric currents wherever there are free electric charges (such as the ionosphere, one of the layers of our atmosphere).
This, in turn, generates more complex magnetic fields that add to the Earth’s magnetic field.
This chaotic disturbance of the magnetic field is called geomagnetic storm. And this, in turn, can disrupt radio and satellite communications. In the most extreme cases, this can even lead to power outages.
Will there be power outages and communication issues?
Currently, the highest alert level published by various space weather observing and forecasting services (such as NOAA, Space Weather or SOHO) is G1.
This alert level corresponds to minor geomagnetic storms, with possible minor fluctuations in the electrical network and a lesser impact on the operation of the satellites. We shouldn’t be worried, should we?
In September 1859, a geomagnetic storm caused by a coronal mass ejection caused Telegraph networks in Europe and North America failed.
The electrical currents induced in the cables reached such intensity that they caused fires in the receivers. There were even cases of electrocuted telegraph operators. This event was called the Carrington event, after the astronomer who observed the eruption, Richard Carrington (1826-1875).
Back then, we were saved by our limited reliance on electronic systems.
Today, we would not be so lucky: our hyper-technological society maintains a blind faith in the resilience of the communication networks on which our cell phones and our computers depend, something that could not be guaranteed in the face of an event of such magnitude. .
So far, the various attempts by governments to deal with this type of threat have been half-hearted, uncoordinated and based on generalities. Our situation is now one of obvious vulnerability.
And even if the frequency of these phenomena should not cease to increase in the years to come, it still seems to us a very distant problem.
The pressing question now is: will we have time to change before the next Carrington event?
* Gonzalo José Carracedo Carballal is a PhD student in astrophysics at the Astrobiology Center (INTA-CSIC), Spain.
David Montes is a professor at the Complutense University of Madrid, Spain.