A massive solar flare from sunspot AR3664 has struck Earth, causing significant disruptions to high-frequency radio signals across Asia, eastern Europe, and eastern Africa.

This X3.98 flare is the largest yet from AR3664 and ranks as the 4th largest of the solar cycle. Solar flares are powerful bursts of electromagnetic radiation categorized by size; X-class flares are the most potent.

The flare also generated a coronal mass ejection (CME), a release of plasma and magnetic fields from the sun, Space.com reported.

This event follows closely on the heels of heightened solar activity from sunspots AR3664 and AR366, prompting NOAA’s Space Weather Prediction Center to issue a G4 geomagnetic storm watch for the weekend.

Written by B.C. Begley