NASA's Fermi mission detects an outburst of high-energy light from a source more than halfway across the universe.
Gamma rays, the highest-energy form of light, can be observed throughout the cosmos. But detecting emissions of very high energy from distant sources is extremely rare. So astronomers were surprised when, in April 2015, NASA's Fermi Gamma-ray Space Telescope saw a spike in gamma rays from a galaxy more than halfway across the universe. The galaxy, known as PKS 1441+25, is a type of active galaxy called a blazar. At its heart lies a monster black hole with a mass estimated at 70 million times the sun's. As material falls toward the black hole, some of it forms dual particle jets that blast out of the disk in opposite directions at nearly the speed of light. Although blazars are the most common sources of gamma rays detected by Fermi, PKS 1441+25 is one of only two such distant objects for which astronomers recorded emissions with energies greater than a hundred billion times that of visible light. Watch the video to learn more.