This phenomenon at moderate intensity was not threatening, but the fact that it went completely unnoticed disturbed the researchers.
Recently, astronomy enthusiasts were able to revel in an extremely rare spectacle with the alignment of Mercury, Venus, Mars, Jupiter and Saturn, which all lined up in an onion row in their order of proximity to the Sun — a an event which had not occurred since 1864. But in the northern hemisphere, the spectacle was sometimes “photobombed” by a phenomenon which was also magnificent, but quite unexpected at this time: auroras.
These magnificent celestial lights are relatively frequent; on the other hand, it is much rarer that they occur without warning. It is because they are directly associated with a cosmological phenomenon that astronomers watch with particular attention: solar flares and geomagnetic storms which result.
Very briefly, a solar flare is neither more nor less than a large emission of particularly intense light. They arise following an upheaval in the magnetic field of the Sun. But they can also be associated with what are called coronal mass ejections, or CMEs.
Astronomers keep an eye out…
During these events, a bubble of superheated charged particles (we speak of plasma) is catapulted at high speed in a specific direction. Sometimes these eruptions can shoot straight for Earth. The particles then collide with the Earth’s magnetic field, which serves as a shield against these phenomena. This flow of solar plasma then crashes into the upper atmosphere, which can sometimes give rise to auroras.
But the most powerful of them can break through this shield and have noticeable effects. Not directly on humans, but on electrical installations and electronic equipment. This is for example what happened around the Easter weekend, when moderate solar flares caused some radio blackouts on Earth (see our article).
And it is precisely for this reason that NASA diligently monitors the dynamics of solar cells. Because in some rare cases, exceptionally intense EMCs are quite capable of grill half of the world’s electronic infrastructure in a few moments, with all the catastrophic consequences that entails.
…but they were still surprised
The agency had therefore anticipated the blackouts of the Easter weekend. The storm of June 26, on the other hand, took everyone by surprise. No astronomer anticipated its arrival when it slammed head-on into Earth’s magnetic shield, with a staggering peak speed measured at 2.52 million km/h — nearly double the average according to the NASA.
Fortunately, according to the report of Spaceweather.com spotted by LiveScience, the intensity of this geomagnetic storm remained quite moderate despite its speed; in any case, no blackout or damage to the infrastructure has been reported. For the general public, the story ends here. On the other hand, for researchers, it is an event that sends shivers down the spine.
They spend so much time watching sunspots precisely to avoid being faced with a fait accompli at the last moment if a storm of critical intensity were to hit the Earth.
There is therefore enough to be at the same time relieved to have had a narrow escape, but also worried to have missed this information. A bit like a pedestrian lost in thought who escaped a frontal impact with a heavy weight in extremis.
A CME from an unexpected area
Since then, the challenge was to determine why and how this storm could have been so discreet. And astronomers finally believe they have a satisfactory answer; for them, this geomagnetic storm was simply not part of a sunspot.
They consider the eruption to have occurred in what is called a co-rotating interaction region, or CIR. This corresponds to an output of crossroads where extremely fast solar winds cross, and other slower ones. This interaction between charged particles can give rise to an accumulation of plasma, which can then be ejected like a cannonball during a jolt of the magnetic field.
But unlike sunspots, astronomers don’t routinely monitor these CIRs, which is why it took everyone by surprise. This story therefore reinforces the idea that it is very unwise to simply monitor sunspots; it’s necessary scrutinize the Sun as a whole, with many distinct techniques.
This would therefore make it possible to be warned as soon as possible if a cataclysmic eruption of the type Carrington Event (see our article) was occurring. This would not fundamentally change the situation since as it stands, humanity remains largely powerless against the whims of its fetish star. But in such a catastrophic context, the smallest minute could make the difference when it comes to protect certain vital systems for Humanity.
In any case, the message is clear: we will have to keep our eyes wide open as we approach the next peak of solar activity, expected between 2023 and 2026.