MAJOR X-CLASS SOLAR FLARE (UPDATED): On Sept. 6th at 1202 UT, sunspot AR2673 unleashed a major X9.3-class solar flare--the strongest solar flare in more than a decade. X-rays and UV radiation from the blast ionized the top of Earth's atmosphere, causing a strong shortwave radio blackout over Europe, Africa and the Atlantic Ocean: blackout map.

Newly arriving images from the Solar and Heliospheric Observatory confirm that the explosion also produced a coronal mass ejection (CME) with an Earth-directed component. Click to view a movie of the plasma cloud racing away from the sun:

The CME will probably reach our planet on Sept. 8th, bringing with it a chance of G2- or G3-class geomagnetic storms.

Many readers are asking about the historic context of this event. How epic is it? Answer: This is a decade-class flare. A list of the most powerful solar flares recorded since 1976 ranks today's flare at #14, tied with a similar explosion in 1990. However, compared to the iconic Carrington Event of 1859, or even the more recent Halloween storms of 2003, this event is relatively mild. Modern power grids, telecommunications, and other sun sensitive technologies should weather the storm with little difficulty.

On the other hand, sky watchers could see some fantastic auroras before the week is over. And ham radio operators will surely be noticing strange propagation effects as the sun exerts its influence on our planet's ionosphere. Stay tuned for updates.