Cosmic rays fired at Earth - now we know where from The violent region at the centre of our galaxy is the prime candidate, after gamma ray analysis, Bill Condie reports. Photo montage of gamma-rays as measured by the HESS array on the night sky over Namibia, with one of the small HESS telescopes in the foreground. Credit: H.E.S.S. Collaboration, Fabio Acero and Henning Gast Astronomers believe they may have identified the source of the stream of cosmic rays that rain down on Earth from outer space. Cosmic rays are extremely high-energy particles such as protons and atomic nuclei....