Using NASA’s Fermi Space Telescope, astronomers have discovered two ghostly gamma-ray jets, which they believe are a sign of earlier jet activity from the central black hole of our galaxy. This artist's conception shows an edge-on view of the Milky Way galaxy. The newly discovered gamma-ray jets, depicted in pink, extend for 27,000 light-years above and below the galactic plane, and are tilted at an angle of 15 degrees. Previously known...