In May 1921, radio communications around the world were disrupted; In January 1938, radio communications in Canada were interrupted for almost twelve hours and trains were stopped in England due to power outages. In March 1989, six million people in Quebec were without power for several hours and satellites temporarily left their orbit. In October 2003, several satellites were damaged when there was a one-hour power outage in Sweden… Period…
In May 1921, radio communications around the world were disrupted; In January 1938, radio communications in Canada were interrupted for almost twelve hours and trains were stopped in England due to power outages. In March 1989, six million people in Quebec were without power for several hours and satellites temporarily left their orbit. In October 2003, a one-hour power outage in Sweden damaged several satellites… What do all these events have in common? They were all caused by a large solar flare.
“In general, we are well protected from the sun,” explains Aurélie Marchaudon, a researcher at the Institute for Astrophysics and Planetary Research (IRAP) in Toulouse. But when solar flares are powerful enough and directed toward Earth, they can cause disruption to our planet.
Peak in mid-2024
Solar flares are sudden flashes of radiation that occur on the surface of the Sun and are generally accompanied by a violent ejection of plasma. The phenomenon is quite common, especially when the Sun reaches a peak of its activity, the solar maximum, which occurs about every 11 years. The next one is coming soon, it is planned for around mid-2024, a year in advance.
The signals are there. For several months we have observed numerous spots on the surface of our star, sometimes visible to the naked eye. The eruptions take place at these points. Since the end of February, auroras caused by solar storms have also been observed at very low latitudes, particularly in France. And on July 3, the largest solar storm in North America in 20 years caused a brief radio blackout.
However, if scientists agree that the Sun will reach a peak of its activity within a few months, it is still impossible to predict where and when exactly the next eruptions will occur, whether they will have an impact on the Earth and for how long will last (a few hours or several days) and how intense they will be.
However, the most extreme damage can damage satellites. By bombarding the ionosphere with energetic and ionized particles, they also increase its density, which can deflect, slow down or absorb satellite signals, depriving aircraft and ships in particular of extremely dangerous GPS. Not to mention, people on a plane can be exposed to high doses of radiation during a solar storm.
“Nowadays the networks are interconnected. For example, if part of the European network fails, this will result in demand shifting to the rest, which will then become overloaded and risk collapsing.”
Another risk is that “these eruptions are sources of strong electrical currents and generate counter-reaction currents on the Earth’s surface,” explains Aurélie Marchaudon. If these countercurrents are at the level of the earth’s crust, which is not very conductive, it is not a problem. But when they touch our electrical installations, they can trip or destroy transformers, as happened in Quebec in 1989. “And today the networks are interconnected. For example, if part of the European network fails, this leads to a shift in demand to the rest, which is then overloaded and at risk of collapsing,” she comments.
Although it is not possible to predict eruptions, instruments are still available to study the Sun and detect an eruption when it occurs. It usually takes several hours for them to reach Earth, which gives time to temporarily turn off the satellites or land aircraft in the area where the eruption will take place, as was the case in Sweden in November 2015. However, when it comes to the power grid: “We cannot switch it off all over the world in a matter of hours,” emphasizes Aurélie Marchaudon.
But to see a solar flare that could cause disruption across the entire planet, we have to go back to 1859. “The Carrington Event,” named after the astronomer who observed it, severely disrupted telecommunications at the time. The most violent known eruption occurred 14,300 years ago. In a study published Oct. 9, scientists say they have discovered an overdose of cosmic radiation from a storm of “never-before-seen proportions” in the rings of subfossil trees found in the French Alps. However, “such a storm today would be catastrophic for our modern technological society,” they warn.