Late in the evening on June 20, 2011 the Sun emitted a long lasting C7.7 class flare (a relatively small flare) that peaked around 11:25p.m. EDT. The flare was associated with a coronal mass ejection that bloomed off the sun at 11:09p.m. EDT (0412 UT).
Spaceweather.com reports that according to analysts at the Goddard Space Flight Center Space Weather Lab, the CME left the sun traveling 800 km/s and it will reach Earth on June 23rd at 23:22 UT (plus or minus 7 hours). A very cool 3D heliospheric model (below) shows the cloud sweeping past our planet. The impact is expected to trigger a G2-class geomagnetic storm.
Update: SDO posted this video of the event
Provided by Universe Today - NASA, Spaceweather.com