Fiery arcs rise above an active region on the surface of the sun in this image taken by NASA’s STEREO (Behind) spacecraft on Jan. 27. The arcs are plasma, superheated matter made up of moving charged particles. Just as iron filings arc from one end of a magnet to another, the plasma is sliding in an arc along magnetic field lines.

Image credit NASA released 2010

January 2010 - Storms on the Sun