Big sunspot AR1520 erupted on July 12th around 16:53 UT, producing an X-class solar flare and hurling a CME directly toward Earth. Forecasters expect the cloud to arrive on July 14th. Its impact could spark moderate to severe geomagnetic storms, allowing auroras to be seen at lower latitudes than usual.
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.
The explosion also strobed Earth with a pulse of extreme UV radiation, shown here in an image captured by NASA's Solar Dynamics Observatory:
Finally, solar protons accelerated by the blast are swarming around Earth. The radiation storm, in progress, ranks "S1" on NOAA space weather scales, which means it poses no serious threat to satellites or astronauts. This could change if the storm continues to intensify.
For more information check with Space Weather.