Music Music Announcer: Five, four, three, engines start, one, zero, and liftoff of the Delta rocket carrying GLAST, a gamma-ray telescope searching for unseen physics in the stars of the galaxies. Narrator: Launched on June 11, 2008, GLAST, renamed the Fermi Gamma-ray Space Telescope, has been collecting gamma-ray data for five years. In that time it has made some astounding observations of some of the most powerful events and objects in the universe. Including some right on our doorstep. Narrator 2: Fermi looks at gamma rays, the highest energy form of light, and it just surprised everyone with a discovery about the fabric of space and time. Julie McEnery: Because Fermi saw no delay in the arrival time of the two photons, it confirms that space and time is smooth and continuous as Einstein had predicted. Narrator 3: With Fermi, astronomers have made the most accurate measurement of starlight in the universe, and used it to establish the total amount of light from all the stars that have ever shown. Narrator 4: In April 2013, a shockingly bright blast of gamma rays from a dying in a distant galaxy, produced the highest-energy light ever detected from such an event. Elizabeth Hays: Every three hours the Large Area Telescope on board Fermi builds up a picture of the sky in gamma rays. One thing it sees a lot of is blazars--active galaxies whose emissions are powered by supermassive black holes. Because we're watching them all the time, we can track their activity and alert other telescopes to new flare-ups. Narrator 5: Two years of scanning the sky with Fermi's Large Area Telescope have set the strongest limits yet for WIMP dark matter. The longer Fermi operates, the better its ability either to box in the nature of dark matter, or to find actual evidence of what it is. Narrator 6: Scientists have recently discovered a gigantic, mysterious structure in our galaxy. This never-before-seen feature looks like a pair of bubbles extending above and below our galaxy's center. Narrator 7: New images show where supernova remnants emit gamma rays a billion times more energetic than visible light. This glow suggests that the remnants are a source of cosmic rays-- protons and electrons accelerated to near light speed. Narrator 8: Observations of two supernova remnants by NASA's Fermi Gamma-ray Space Telescope conclusively show these supernova remnants are accelerating protons. When they strike protons in nearby molecular clouds, they produce the gamma-ray emission Fermi sees. Narrator 9: Recently, astronomers have observed incredible flares in the nebula that theorists are hard-pressed to explain. The gamma rays most likely arise from electrons moving near the speed of light, but to account for these flares, the electrons must have the highest energies ever seen in cosmic sources. Narrator 10: In three years Fermi has detected more than 100 gamma-ray pulsars. And about a third of gamma-ray pulsars were discovered by Fermi on the basis of their gamma-ray pulsations alone. Narrator 11: In late 2010, NASA's Fermi Gamma-ray Space Telescope watched the system glow with faint gamma emission as the pulsar first approached the disk. Astronomers expected the same behavior in early 2011 when the outbound pulsar grazed the disk again, but, instead, Fermi detected intense and puzzling gamma-ray flares. Roger Romani: We managed to get enough observations of the object to piece together its orbital period. And found, remarkably, that it was an incredibly heated object--blue white on one side, deep, deep red on the other-- and it was orbiting around an energetic pulsar with an orbital period of about one-and-a-half hours. The gamma rays are blasting the companion at point-blank range. Narrator 12: Fermi found that star birth and death in the Cygnus X star factory corrals particles and boosts them to cosmic-ray energies. Narrator 13: In early March 2012, a powerful flare erupted on the sun During this event, the LAT detected the highest energy light every recorded from a solar flare. Narrator 14: New observations by NASA's Fermi Gamma-ray Space Telescope show that thunderstorms make antimatter. The process starts with a terrestrial gamma-ray flash, or TGF; an intense pulse of gamma rays originating from thunderstorms. Narrator 15: Scientists have discovered that radio signals, once thought to be produced by the lighting that triggers a TGF, are in fact broadcast by TGFs themselves. Eric Stoneking: There was a defunct Russian satellite in an orbit that would intersect Fermi's orbit in about a week. Julie McEnery: Those two spacecraft were occupying the same space within 30 milliseconds of each other. That's why this was scary. Having done the maneuver, and avoided a collision means we continue operating, so continue doing the great science that we have been doing over the past four-and-a-half years. Music Beeping Beeping