On Feb. 13th at 1738 UT, sunspot 1158 unleashed the strongest solar flare of the year so far, an M6.6-category blast.
The eruption produced a loud blast of radio waves heard in shortwave receivers around the dayside of our planet. In New Mexico, amateur radio astronomer Thomas Ashcraft recorded these sounds at 19 to 21 MHz. "This was some of the strongest radio bursting of the new solar cycle," he says. "What a great solar day."
Preliminary coronagraph data from STEREO-B and SOHO agree that the explosion produced a fast but not particularly bright coronal mass ejection (CME). The cloud will likely hit Earth's magnetic field on or about Feb. 15th. High-latitude sky watchers should be alert for auroras.
Barely visible when the weekend began, the active region is now more than 100,000 km wide with more than half-a-dozen Earth-sized dark cores scattered beneath its unstable magnetic canopy. More Earth-directed eruptions are likely in the hours ahead.