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A surprise solar storm hit the Earth at over 2,500,000 km / h

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This moderate intensity phenomenon was not threatening, but the fact that it went completely unnoticed bothered the researchers.

Recently, astronomy enthusiasts were able to enjoy an extremely rare sight with the alignment of Mercury, Venus, Mars, Jupiter and Saturn, all lined up in a row of onions in the order of proximity to the Sun, an event that was not it took place from 1864. But in the northern hemisphere, the spectacle was sometimes “photo-bombed” by a phenomenon that was also magnificent, but completely unexpected at that moment: the 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 observe with particular attention: solar flares And geomagnetic storms which result.

In short, a solar flare is neither more nor less than a large emission of particularly intense light. They arise as a result of an upheaval in the Sun’s magnetic field. But they can also be associated with what is called coronal mass ejections, or CMEs.

The geomagnetic storms that cause auroras usually come from coronal mass ejections, plasma bubbles originating from sunspots. © SDO / HMI

Astronomers keep an eye on …

During these events, a bubble of superheated charged particles (we speak of plasma) is catapulted at high speed in a certain direction. Sometimes these eruptions can shoot directly towards the Earth. The particles then collide with the Earth’s magnetic field, which acts as a shield against these phenomena. This stream 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 systems and electronic equipment. This is for example what happened around 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 half grid of the world’s electronic infrastructure in a few moments, with all the catastrophic consequences that this entails.

An example of a solar flare captured on March 30 by NASA’s Solar Dynamics Observatory. © NASA / GSFC / SDO

… 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 predicted its arrival when it crashed head-on into Earth’s magnetic shield, with a jaw-dropping peak speed measured at 2.52 million km / h, nearly double the average, according to NASA.

Fortunately, according to the Spaceweather.com report identified by LiveScience, the intensity of this geomagnetic storm remained fairly moderate despite its speed; in any case, no blackouts or damage to infrastructures were reported. For the general public, the story ends here. On the other hand, for researchers, it’s a shivering event down the spine.

They spend so much time looking at 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 lifted up to have had a loophole for a hair, but also worried that I have lost this information. A bit like a pedestrian lost in his thoughts who escaped a frontal impact with a heavy weight in extremis.

An ECM from unexpected territory

Since then, the challenge has been 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 simply wasn’t part of a sunspot.

They believe the eruption occurred in what is called a co-rotating interaction region or CIR. This corresponds to an output of crossroads where extremely fast and slower solar winds meet. This interaction between charged particles can result in an accumulation of plasma, which can then be ejected like a cannonball during a shock of the magnetic field.

But unlike sunspots, astronomers don’t regularly monitor these CIRs, which is why it took everyone by surprise. This story therefore reinforces the idea that it is not wise to simply monitor sunspots; need scrutinizing the Sun as a whole, with many distinct techniques.

This would then allow you to be notified as soon as possible in the event of a catastrophic eruption of the type Carrington event (see our article) occurred. This it would not substantially change the situation for as it is, humanity remains largely helpless against the whims of its fetish star. But in such a catastrophic context, the smallest minute could make all the difference protect some vital systems for Humanity.

Either way, the message is clear: we will need to keep our eyes peeled as we approach the next peak of solar activity, expected between 2023 and 2026.

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