New X class flare

X-FLARE: Sunspot 930 has just unleashed another big solar flare, an X3-class explosion at 0240 UT on Dec. 13th.

As a result of the blast, a radiation storm is underway. Based on the energy and number of solar protons streaming past Earth, NOAA ranks the storm as category S2: satellites may experience some glitches and reboots, but astronauts are in no danger.

The explosion probably hurled a coronal mass ejection toward Earth. (Confirmation from SOHO is still pending.) Sky watchers should be alert for auroras when it arrives on Dec. 14th or 15th.

NOTE: A radiation storm just underway has overwhelmed solar wind sensors onboard NASA's ACE spacecraft.