The sun erupted late on January 22, 2012 with an M8.7 class flare, an earth-directed coronal mass ejection (CME), and a burst of fast moving, highly energetic protons known as a "solar energetic particle" event.

The latter has caused the strongest solar radiation storm since September 2005 according to NOAA's Space Weather Prediction Center.

NASA's Goddard Space Weather Center's models predict that the CME is moving at almost 1,400 miles per second, and could reach Earth's magnetosphere - the magnetic envelope that surrounds Earth - as early as tomorrow, Jan 24 at 9 AM ET (plus or minus 7 hours).

This has the potential to provide good auroral displays, possibly at lower latitudes than normal.