Big sunspot AR1520 unleashed an X1.4-class solar flare on July 12th. Because the sunspot is directly facing Earth, everything about the blast was geoeffective. For one thing, it hurled a coronal mass ejection (CME) directly toward our planet. According to a forecast track prepared by analysts at the Goddard Space Weather Lab, the CME will hit Earth on July 14th around 10:20 UT (+/- 7 hours) and could spark strong geomagnetic storms. Sky watchers should be alert for auroras this weekend.
For those interested, feel free to track the progress using SGO's real-time data site: http://www.sgo.fi/Data/RealTime/