These images encapsulate 25 years of progress in gamma-ray astrophysics. Top: The EGRET sky as seen in gamma rays above 100 MeV. Brighter colors indicate greater numbers of gamma rays. Its most prominent feature is the central plane of the galaxy, which runs across the middle of the map, a result of gamma rays produced when accelerated particles strike interstellar gas and starlight. The largest yellow spot on the right side of the plane is the Vela pulsar, one of five new gamma-ray pulsars EGRET discovered. The prominent reddish blob at top right is the blazar 3C 279. Bottom: The all-sky map produced by Fermi's Large Area Telescope (LAT), using data from August 4, 2008, to August 4, 2015, is sharper, more detailed and shows higher-energy gamma rays than EGRET's. In fact, the LAT has now captured more high-energy gamma rays from a single source, the Vela pulsar, than the total number detected by EGRET.