EARTH-DIRECTED SOLAR FLARE: On Feb. 13th at 1738 UT, sunspot 1158 unleashed the strongest solar flare of the year so far, an M6.6-category blast. NASA's Solar Dynamics Observatory recorded an intense flash of extreme ultraviolet radiation, circled below:
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-A 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.
The source of this activity, sunspot 1158 is growing rapidly (48 hour movie). The active region is now more than 100,000 km wide with at least a dozen Earth-sized dark cores scattered beneath its unstable magnetic canopy. More Earth-directed eruptions are likely in the hours ahead.
more images: from Luca Tesoro of Mercogliano (AV), Italy; from Michael Buxton of Ocean Beach, California; from Strikis Iakovos - Marios of Athens Greece (Haidari)