During a December 2013 solar flare, three solar-watching satellites — NASA’s Solar Dynamics Observatory (SDO), the agency’s Solar and Terrestrial Relations Observatory (STEREO), and JAXA/NASA’s Hinode — observed an electromagnetic phenomenon called a current sheet, a strong clue for explaining what initiates solar flares. This picture shows four views of the 10 December 2013 solar flare from SDO, STEREO, and Hinode. The current sheet...
