Solar Flare in the Gamma-ray Sky
What shines in the gamma-ray sky? The answer is usually the most exotic and energetic of astrophysical environments, like active galaxies powered by supermassive black holes, or incredibly dense pulsars , the spinning remnants of exploded stars. But on March 7 , a powerful solar flare, one of a series of recent solar eruptions , dominated the gamma-ray sky at energies up to 1 billion times the energy of visible light photons . These two panels illustrate the intensity of that solar flare in all-sky images recorded by the orbiting Fermi Gamma-ray Space Telescope . On March 6, as on most days, the Sun was almost invisible to Fermi's imaging detectors. But during the energetic X-class flare , it became nearly 100 times brighter than even the Vela Pulsar at gamma-ray energies. Now faded in Fermi's view , the Sun will likely shine again in the gamma-ray sky as the solar activity cycle approaches its maximum.