The ESA's Integral gamma-ray observatory has resolved the diffuse glow from the heart of the Milky Way into hundreds of individual sources, solving a mystery that has stumped astronomers for more than 30 years. Astronomers believed that the gamma ray glow came from the interactions of atoms, but this couldn't explain why the glow was so strong. Integral was able to see the individual celestial objects, and the data suggests that they might be binary systems, where a black hole or neutron star is orbiting another star.