2023-10-19 14:22:06
May 1921, radio communications throughout the world were disrupted; January 1938, radio transmissions were interrupted for nearly 12 hours in Canada and electrical failures caused trains to stop in England; March 1989, six million people found themselves without electricity for several hours in Quebec and satellites temporarily left their orbit; October 2003, several satellites were damaged while a one-hour power outage occurred in Sweden… Period…
May 1921, radio communications throughout the world were disrupted; January 1938, radio transmissions were interrupted for nearly 12 hours in Canada and electrical failures caused trains to stop in England; March 1989, six million people found themselves without electricity for several hours in Quebec and satellites temporarily left their orbit; October 2003, several satellites were damaged while a one-hour power outage occurred in Sweden… 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, researcher at the Institute for Research in Astrophysics and Planetology (IRAP) in Toulouse. But when solar flares are strong enough and oriented toward Earth, they can create disturbances on our planet.
Pic mi-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, particularly when the Sun reaches a peak of activity, the solar maximum, which occurs approximately every 11 years. The next one is close, it is scheduled 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. It is at the level of these spots that the eruptions take place. Since the end of February, polar auroras, caused by solar storms, have also been seen at very low latitudes, notably in France. And on July 3, the biggest solar storm in the last 20 years caused a brief radio blackout in North America.
But if scientists agree that the Sun should reach a peak of activity within a few months, it is nevertheless impossible to predict where and when exactly the next eruptions will take place, if they will affect the Earth, for how long they will last (a few hours or several days) and what their intensity will be.
What consequences?
However, the most extreme ones are likely to 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 and therefore deprive planes and ships, in particular, of GPS, which is extremely dangerous. Not to mention that people in a plane in flight during a solar storm can find themselves exposed to high doses of radiation.
“Today the networks are interconnected, if part of the European network falls for example, this will cause a transfer of demand to the rest, which will find itself overloaded and risks falling in turn”
Another risk is that “these eruptions are sources of intense electrical currents and generate counter-reaction currents on the Earth’s surface,” explains Aurélie Marchaudon. When these countercurrents are located at the level of the earth’s crust, which is not very conductive, it is not serious. But if they touch our electrical installations, they can trip or destroy transformers, like in 1989 in Quebec. “And today the networks are interconnected, if part of the European network falls, for example, this will cause a transfer of demand to the rest, which will find itself overloaded and risks falling in turn,” comments -She.
“Never seen scale”
Although it is not possible to predict eruptions, there are still tools available to study the sun and detect an eruption when it occurs. These generally take several hours to reach Earth, this gives time to temporarily turn off the satellites, or to ground planes in the area where the eruption will strike, as was the case in November 2015 in Sweden. As for the electricity network, on the other hand… “We cannot turn it off throughout the world in a few hours,” emphasizes Aurélie Marchaudon.
But to see a solar flare capable of creating disturbances across the entire planet, we have to go back to 1859. “The Carrington event”, named following the astronomer who observed it, had then greatly disrupted telecommunications. . As for the most violent eruption known, it dates back 14,300 years. In a study published on October 9, scientists explain having discovered in the rings of subfossil trees found in the French Alps an overdose of cosmic radiation from a storm of “never before seen magnitude”. However, “such a storm today would be catastrophic for our modern technological society,” they warn.
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