Our Fermi Gamma-ray Space Telescope has found a signal at the center of the neighboring Andromeda galaxy. Could it indicate the presence of the mysterious stuff known as dark matter? Astronomers don't know yet. The gamma-ray signal is similar to one seen by Fermi at the center of our own Milky Way galaxy. Learn more: http://go.nasa.gov/2mjDvWj | NASA - National Aeronautics and Space Administration