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 temporarily interrupted.
It had ocurred a solar flare. That is, a sudden emission of electromagnetic radiation and energy particles located in a small region of the solar atmosphere. In that region the magnetic fields are especially strong and complex.
Often times, a solar flare precedes a much more impressive event. The same magnetic field that generated the explosion writhes under the Sun’s surface, drawing huge amounts of solar plasma outward and, like a cannon, launching it at high speeds into space.
This is a coronal mass ejection. Unlike the radiation from an ordinary flare (which hits Earth at the speed of light, around 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’s orbit.
And this is what happened. Last week there were different eruptions of moderate intensity until, on July 15, one of them was accompanied by a spectacular ejecta.
Of course, with a peculiarity: this time, it is directed to our planet. And we look forward to this Thursday, July 21.
history repeats itself
This is not the first time we have found ourselves in this situation. Although the physics of these phenomena is not fully understood, we are confident that their nature is primarily magnetic.
And also that its occurrence is not fortuitous: approximately every 11 years our Sun goes through periods of high magnetic activity (called solar maxima).
During maxima, the frequency of these events is especially high. Right now 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 aurorae. However, the effects of greater global reach occur when it interacts with the so-called terrestrial magnetosphere: a kind of protective bubble that surrounds the Earth, in which the intensity of the terrestrial magnetic field is capable of deflecting the charged particles released by the Sun. (the solar wind).
This allows, among other things, the Earth to retain its atmosphere.
Upon coming into contact with an ejection, the magnetosphere is compressed and interacts with it, modifying its structure. The Earth’s rapidly changing magnetic field produces induced electrical currents wherever there are free electrical 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 own magnetic field.
This chaotic disturbance of the magnetic field is called geomagnetic storm. And it can, in turn, disrupt radio and satellite communications. In the most extreme cases, it can even lead to power outages.
Will there be power outages and communication problems?
At the moment, the highest alert level published by different space weather observation and prediction 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 less impact on satellite operations. We shouldn’t worry, right?
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 an 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 hypertechnological society maintains a blind faith in the resilience of the communication networks on which our cell phones and computers depend, something that could not be guaranteed in the face of an event of such magnitude.
Until now, the different attempts by governments to deal with this type of threat have been timid, uncoordinated and based on generalities. Our situation is now one of clear vulnerability.
And although the frequency of these phenomena is not expected to stop increasing in the coming years, it still seems like a very distant problem to us.
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 Center for Astrobiology (INTA-CSIC), in Spain.
David Montes is a professor at the Complutense University of Madrid, Spain.
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