This Shower of Gamma Rays Is from a Flaring Blazar 5 Billion Years Ago

Five billion years ago, a blazar abruptly flared, triggered an intense rain of gamma rays. Racing across the universe for millennia, they finally slammed into NASA’s Fermi satellite over several days this June, setting a new record for the most luminous high-energy object we’ve ever seen. »7/11/15 1:39pm7/11/15 1:39pm