Giant bubbles of hot gas erupt from the core of the Milky Way galaxy in this artist's concept. The galaxy's thin disk is shown edge-on, with the bubbles billowing thousands of light-years into intergalactic space. Known as Fermi bubbles for their discovery by the Fermi space telescope, they may have been created by eruptions in a disk of gas close to the galaxy's central black hole. The bubbles are visible only to space telescopes that are sensitive to gamma rays and X-rays. [NASA/GSFC]