NASA, NOAA and SpaceWeather announce that a solar ejection will reach our planet on July 21. Will it cause a geomagnetic storm? Will it cause disturbances in satellite communications and power outages?
Something is happening to our Sun. On July 11, one of the regions of the solar atmosphere currently exhibiting sunspots caught the attention of observatories due to a sudden increase in its brightness in ultraviolet and X-rays. Noticing it were radio amateurs on both sides of the Pacific Ocean, seeing their communications briefly interrupted.
A solar flare had just occurred. That is, a sudden emission of electromagnetic radiation and energetic particles located in a small region of the solar atmosphere. A region where, in addition, the magnetic field is especially strong and complex.
On many occasions, a solar flare precedes a much more impressive event. The same magnetic field that generated such a flare writhes under the Sun's surface, dragging huge amounts of solar plasma out of it and, like a cannon, launching them at high speed into space. We speak then of a coronal mass ejection. Unlike the radiation from a flare (which reaches the Earth at the speed of light, around 8 minutes), coronal mass ejections are made up of charged particles moving at a certain speed. This implies that they can take between a few hours to several days to reach Earth's orbit.
And so it ended up being. Different flares of moderate intensity continued to occur during the past week until, on July 15, one of them was accompanied by a spectacular ejection. Of course, with a peculiarity: this time, it is directed towards our planet. And we hope to be reached by her on July 21.
history repeats itself
It is not the first time that we see each other in these. Although today the physics of these phenomena is not fully understood, we are certain that their nature is mainly magnetic. And also that its occurrence is not fortuitous: approximately every 11 years, our Sun experiences periods of high magnetic activity (called solar maxima).
During these maxima, the frequency of these events is especially high. And right now we are entering the maximum of the current cycle, whose peak of activity is expected to be reached throughout the year 2024.
The outreach of a coronal mass ejection is often accompanied by striking aurorae. However, the effects with more 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 preserve its atmosphere.
Upon contact with an ejection, the magnetosphere is compressed and interacts with it, modifying its structure. The rapid variations of the Earth's magnetic field produce 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 a geomagnetic storm. And it can, in turn, cause disturbances in radio and satellite communications. In the most extreme cases, even power outages.
Representation of the interaction of the solar wind with the Earth's magnetosphere. /
Will there be power outages and communication problems?
At the moment, the highest alert level published by the 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 small fluctuations in the electrical network and reduced impact on satellite operations. We shouldn't worry, right?
The truth is that this might not have been the case. In September 1859, a geomagnetic storm caused by a coronal mass ejection caused telegraph networks in Europe and North America to fail. The electrical currents induced in the cables reached such an intensity that they caused fires in the receivers. There were even cases of electrocution by telegraph operators. It was named the Carrington event, after the astronomer who observed the flare, Richard Carrington.
Back then we were saved by our limited reliance on electronic systems. Today we would not be so lucky: our hypertechnified society maintains blind faith in the resilience of the communication networks on which our mobile phones and computers depend, something that could not be guaranteed in an event of such magnitude.
For now, the different attempts carried out by the States to address this type of threat have been timid, uncoordinated and based on generalities. Our situation right now is one of clear vulnerability. And although the frequency of these phenomena is not expected to stop increasing in the coming years, it still seems to us to be a problem that is too foreign.
The question to ask now is, will we have time to change our minds before the next Carrington event?
This article has been published in 'The Conversation'.