What you need to know about the huge sunspot looking back at Earth

The perpetrator? A geomagnetic storm, fueled by high-energy particles and magnetism from a sunspot: a bruise-like discoloration on the surface of the sun. The same sunspot cluster, which has been hiding at the back of the sun for several weeks, is now turning back towards Earth.

There is a chance that more geomagnetic storms of varying strength are on the way over the next two weeks as the sunspot moves from left to right across the solar disk. (It takes about 27 days for the Sun to rotate once.) It is unlikely that another extreme geomagnetic storm will occur in the near future, but moderate to severe geomagnetic storms are not out of the question if a solar eruption emerges from the favorably positioned sunspot . TROS.

This is technically the third time this sunspot cluster has looked at Earth. He focused on us for the first half of May, then returned at the end of the month, early June. Now Earth is once again in the line of fire.

Each time the sunspot cluster returns to the Earth-facing side of the Sun, it is assigned a new number. In May it was “Active Region 3664.” Then 3697. Now it’s AR3723 – and it crackles with magnetism.

On Sunday, for example, AR3723 spewed out an M-class solar flare. That’s the second highest level on the scale (it’s A, B, C, M, and X, with X-class flares being the largest). The radiation pulse helped ionize Earth’s upper atmosphere, causing a shortwave radio blackout over the Atlantic Ocean for several hours. And AR3723 is ready to spit out even more magnetic glitches in the coming days and weeks.

Solar flares are intense explosions of high-energy particles and electrons that hurtle through space at nearly the speed of light. They appear as intense flashes of light that flicker on the sun. Sometimes slower-moving shock waves of magnetism follow, known as coronal mass ejections (CMEs); they rush through space like interstellar tsunamis. When a CME strikes Earth, its chaotic magnetism can interact with Earth’s magnetic field, causing episodes of the Northern (and Southern Lights).

It’s too early to know exactly what AR3723 has in store.

It will take another day or so before the observation satellites become more visible, which will help scientists at the Space Weather Prediction Center in Boulder, Colorado, better determine their magnetic structure. From there, the scientists can make probabilistic predictions, for example projecting the probability of a class M or X solar flare within a certain time frame. These flares send high-energy particles toward Earth, which can lead to shortwave radio blackouts on the sunlit side of the planet.

The sunspot cluster is much smaller than it once was. But its magnetic structure is apparently still sufficient to spit out strong flares. The Space Weather Prediction Center noted that AR3723 “remained the most magnetically complex spot group” but had not evolved much over the past day.