Fermi's Motion Produces a Study in Spirograph
NASA's Fermi Gamma-ray Space Telescope orbits our planet every 95 minutes, building up increasingly deeper views of the universe with every circuit. This image compresses eight individual frames, from a movie showing 51 months of position and exposure data by Fermi's Large Area Telescope (LAT), into a single snapshot. The pattern reflects numerous motions of the spacecraft, including its orbit around Earth, the precession of its orbital plane, the manner in which the LAT nods north and south on alternate orbits, and more.
The LAT sweeps across the entire sky every three hours, capturing the highest-energy form of light —gamma rays — from sources across the universe. These range from supermassive black holes billions of light-years away to intriguing objects in our own galaxy, such as X-ray binaries, supernova remnants and pulsars.