A coronal mass ejection (CME) propelled toward Earth by the X2-flare of Feb. 15th should arrive during the late hours of Feb. 17th--that's today. A moderately strong geomagnetic storm is likely when it arrives. High-latitude sky watchers should be alert for auroras after nightfall.

NASA's researchers have made a time-lapse movie of the Feb. 17th explosion. Watch the video below then scroll down for commentary:



This is a composite of data from two spacecraft: SOHO and the Solar Dynamics Observatory (SDO). SDO took the golden picture in the middle; it's an extreme ultraviolet image of the sun. A flash of UV radiation centered on sunspot 1158 marks the biggest solar flare since Dec. 2006. SOHO took the red picture on the outside; it's a coronagraph image. The CME en route to Earth now is visible as a willowy cloud flying away from the solar disk.

More images and movies of this event may be found here.