Fermi’s 14-Year Time-Lapse of the Gamma-Ray Sky

The entire gamma-ray sky is unwrapped into a rectangular map, with the center of our Milky Way galaxy located in the middle, in this 14-year time-lapse of the gamma-ray sky. A moving source, our Sun, can be seen following a curving path through the sky, a reflection of Earth’s annual orbital motion. Watch for strong flares that occasionally brighten the Sun. The central plane of our galaxy is on full display, glowing in gamma rays produced when accelerated particles (cosmic rays) interact with interstellar gas and starlight. Pulsars and supernova remnants, all bright gamma-ray sources for Fermi, also fleck the Milky Way band. Above and below the bright central plane, where our view of the broader cosmos becomes clearer, splotches of color brighten and fade. These sources are jets of particles moving at nearly the speed of light driven by supermassive black holes in distant galaxies. The jets happen to point almost directly toward Earth, which enhances their brightness and variability. Over a few days, these g