This image shows pulsed gamma rays from the Vela pulsar as constructed from photons detected by Fermi's Large Area Telescope. The Vela pulsar, which spins 11 times a second, is the brightest persistent source of gamma rays in the sky. The bluer colour in the latter part of the pulse indicates the presence of gamma rays with energies exceeding a billion electron volts (1 GeV). For comparison, visible light has energies between two and three electron volts. Red indicates gamma rays with energies less than 300 million electron volts (MeV); green, gamma rays between 300 MeV and 1 GeV; and blue shows gamma rays greater than 1 GeV. The image frame is 30 degrees across. The background, which shows diffuse gamma-ray emission from the Milky Way, is about 15 times brighter here than it actually is.