Record Solar Activity Causes Radio Blackouts Over America Days After Aurora

The biggest solar flare in nearly 20 years has erupted from the sun, sparking radio blackouts across North and South America.

It was rated an X8.7-class flare—the most powerful since 2005—and was produced by the same sunspot that caused the spectacular northern lights displays over the weekend.

Solar flares like this one trigger radio blackouts because they ionize the Earth’s ionosphere and absorb radio waves instead of reflecting them, hampering long-distance radio communication.

This solar flare on May 14, 2024, was also the largest of this solar cycle, which is the sun’s 11-year-long period of magnetic activity. The current solar cycle began in 2019, and we are approaching the solar maximum, which is due to occur between now and the end of 2025.

“The number of sunspots on the sun, which is correlated to solar activity, flares and solar storms, follows an 11-year cycle. Measurements started in 1755, and this is cycle 25. It began in December of 2019 and will last until about 2030. Although the predictions about the activity level in this cycle suggested a quiet period, the sun has been significantly more active than normal during this cycle,” Roger Dube, a professor of physics at the Rochester Institute of Technology in New York, told Newsweek.

Solar flares, which take 8 minutes to reach earth, are bursts of X-rays and ultraviolet radiation from the sun, released from areas of intense magnetic activity like sunspots. They are classed by size as A, B, C, M, or X-class, with X being 10 times stronger than M, and M being 10 times stronger than C.

“A severe X10-class flare could happen roughly eight times during that 11-year period. And a minor M flare can occur about 2,000 times in that cycle,” Daniel Brown, an associate professor in astronomy and science communication at Nottingham Trent University in the U.K., previously told Newsweek.

This X8.7 flare only just skimmed past the Earth, triggering a radio blackout and loss of signal at all frequencies below 30 MHz over the Americas. The reason for this is that the flare was produced from the same sunspot that released the train of coronal mass ejections that triggered the enormous G5 geomagnetic storm on Friday night, resulting in auroras being seen across all 50 U.S. states.

This sunspot, named AR3663, is about 15 times as wide as Earth, and has slowly been moving away from us as the sun rotates, meaning that any solar ejections from this region aren’t aimed directly at Earth anymore.

X-class flares can also lead to radiation storms that affect satellite activity, and expose airlines or astronauts to increased levels of solar radiation. The most powerful X-flare that we have ever measured was the 2003 X28-class flare, but the Carrington Event in 1859 is thought to have been the strongest solar flare in history, causing fires in some telegraph stations.

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