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Sunspot Region AR3697 (formerly known as AR3664) has erupted with powerful solar flares, making headlines once again. This persistent sunspot, notorious for the historic geomagnetic storm that led to global auroras in May, has now produced the strongest radiation storm since 2017, according to NOAA’s Space Weather Prediction Center (SWPC).

On Saturday, June 8, the sunspot fired off an M9.7-class solar flare, the second most powerful type on the classification scale. This intense burst of electromagnetic radiation was strong enough to trigger an S3-level radiation storm on NOAA’s Space Weather Scale, causing a significant radio blackout in the northern polar region. These events can pose risks to space launch operations and satellites, and can disrupt shortwave radio signals.


Solar flares are classified into lettered groups—X, M, C, B, and A—based on their size, with X-class flares being the most powerful. M-class flares, like the recent one from AR3697, are 10 times weaker than X-class flares but 10 times stronger than C-class flares.


Following the flare, energetic protons began their journey toward Earth, interacting with Earth’s magnetic field upon arrival. This interaction caused a polar cap absorption (PCA) event, absorbing shortwave radio transmissions at the poles, similar to an event in July 2023.


The M9.7-class flare also hurled a coronal mass ejection (CME) toward Earth, which could lead to a geomagnetic storm as it approaches Earth’s outer atmosphere. Although not expected to be as intense as May’s solar storm, NOAA’s SWPC has issued a Geomagnetic Storm Watch for G2-level conditions. If conditions are right, the aurora might be visible from some northern and upper Midwest states, from New York to Idaho, on the night of June 10.


On Monday, June 10, AR3697 produced an even stronger solar flare, an X1.5-class flare at 7:08 a.m. EST (1108 GMT). This flare could cause temporary or complete loss of high-frequency (HF) radio signals on Earth’s sunlit side. The SWPC forecasts that solar activity will remain at minor to moderate levels as AR3697 rotates out of sight in the coming days.


For more information and to keep up with the latest forecasts, visit [SWPC’s website](

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