Sun smacks Earth with 2 powerful, back-to-back X-class solar flares, knocking out radio signals across the US

• The sun struck Earth with two powerful X-class solar flares in the past few days.
• The flares caused radio blackouts in the US and Canada.

For the second time in two days, the sun flashed a powerful solar flare at Earth on Monday, Gizmodo reported.

The X-ray and ultraviolet radiation caused a radio blackout for most of the US and Canada, solar physicist Keith Strong said on X, formerly Twitter.

"Frequencies below 5 Mhz were most affected, and navigation signals degraded," Strong wrote.

Solar radiation can ionize the upper atmosphere, which makes for spectacular aurora borealis. However, it's also where high-frequency radio waves travel. So when high-energy solar radiation strikes, it can cause those radio signals to degrade.

The flare that struck Earth on Monday was an X1.5 flare, NASA reported.

X-class flares are the most intense types of solar flares, and a strong one can expose astronauts and space passengers traveling over polar regions to potentially harmful radiation as well as damage satellites, per Space.com. "The current event, a mild category 1, should, however, be rather harmless," Space.com reported.

The X-class flare peaked at 4:46 p.m. ET on Monday. Two days earlier, on August 5, another solar flare peaked at 6:21 p.m. ET.

Why solar flares keep hitting Earth

Solar cycles typically last about 11 years. Over that time, the sun goes through a series of high- and low-activity periods.

Right now, the sun is growing more active, inching closer to peak activity, aka solar maximum.

That peak in solar activity was expected in 2025. But a surprising increase in the number of sunspots this year and the frequency of solar flares suggests that the peak could come sooner than expected — at the end of 2023.

The last solar maximum, between 2012 and 2014, was fairly weak compared to typical solar maximums. But a strong solar maximum can cause extreme space weather events, including back-to-back X-class solar flares like what recently occurred.

This year's X-class solar flares have been on the lower end of the intensity spectrum, with the biggest, an X2.2, occurring in February.

While this year's flares have routinely affected radio signals, a solar flare of X28 — like the one detected in 2003 — would be incredibly destructive for Earth's technology. More-intense flares can damage the power grid, destroy satellites, and scramble GPS.