A strong solar flare

"Sunspot 1283 erupted with another flare yesterday that peaked at 6:20 PM ET. This was an X2.1 class flare, some four times stronger than the earlier flare. Flares can affect Earth's ionosphere, through which high frequency radio waves travel, and cause radio blackouts. This strength flare can cause a "strong" radio blackout, categorized as R3, which has the potential to cause about an hour-long blackout.

This flare, too, had a coronal mass ejection (CME) – an eruption of a giant cloud of solar material -- associated with it. Early models suggest that both CMEs will not travel directly toward Earth, but perhaps just graze our atmosphere in the North, potentially causing auroras in the northern latitudes."


Found here: http://spacestation-shuttle.blogspot.com/2011/09/x21-solar-flare-and-cme.html