The powerful solar flare, observed March 7 by the Fermi Gamma-ray Space Telescope, produced such an outpouring of gamma rays -- a form of light with even greater energy than X-rays -- that the sun briefly became the brightest object in the gamma-ray sky, NASA said Monday.
"For most of Fermi's four years in orbit, its LAT saw the sun as a faint, steady gamma-ray source thanks to the impacts of high-speed particles called cosmic rays," Nicola Omodei, an astrophysicist at Stanford University, said. "Now we're beginning to see what the sun itself can do."
The March flare produced high-energy gamma rays for about 20 hours, two and a half times longer than any event on record, researchers said.
Solar eruptions are increasing as the sun moves toward the peak of its roughly 11-year-long activity cycle, expected in mid-2013, they said.