"The bright, steady gamma-ray glow of the Milky Way is punctuated by intense, days-long flares of near-light-speed jets powered by supermassive black holes in the cores of distant galaxies," said Seth Digel, a senior staff scientist at SLAC National Accelerator Laboratory in Menlo Park, California, who created the images. "These dramatic eruptions, which can appear anywhere in the sky, occurred millions to billions of years ago, and their light is just reaching Fermi as we watch."

Gamma rays are the highest-energy form of light. The movie shows the intensity of gamma rays with energies above 200 million electron volts detected by Fermi's Large Area Telescope (LAT) between August 2008 and August 2022. For comparison, visible light has energies between 2 and 3 electron volts. Brighter colors mark the locations of more intense gamma-ray sources.