The Milky Way is blowing bubbles of cosmic proportions.
Twin bubbles of gamma ray–emitting gas, each the size of a small galaxy, sit above and below the center of the Milky Way like the ends of a giant dumbbell, astronomers have discovered.
Douglas Finkbeiner of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and his colleagues analyzed data from NASA’s Fermi Gamma-ray Space Telescope to find the bubbles, which may have been generated in the galaxy’s core by a long-ago burst of star formation or by a past eruption from the supermassive black hole believed to lie there.