GEOMAGNETIC STORM WATCH (G2): The big storm is over. Now for the little storm. NOAA forecasters say that minor (G1) to moderate (G2) geomagnetic storms are possible today in response to a glancing-blow CME from departing sunspot AR3664. Aurora alerts: SMS Tex t

STRONGEST SOLAR FLARE OF THE CURRENT CYCLE: Sunspot AR3664 just unleashed the strongest solar flare of the current solar cycle--an X8.7-category blast from beyond the sun's western limb. X marks the spot in this image of the flare from NASA's Solar Dynamics Observatory:

Because the sunspot is behind the edge of the solar disk, the flare was partially eclipsed. It was probably even stronger than it appeared. "X8.7" is almost certainly an underestimate of the flare's true strength.

Extreme ultraviolet radiation from the flare ionized the top of Earth's atmosphere, causing a deep shortwave radio blackout over the Americas. Ham radio operators, aviators and mariners may have noticed a sudden loss of signal at all frequencies below 30 MHz.

Subatomic debris from this event might soon reach Earth, guided toward our planet by the Parker Spiral (read the story below for more information). Also, a CME might be in the offing.