Yet another mystery of space has been at least partially explained now. 

For many decades (since 1912 to be precise) it has been known that the Earth is constantly being hit by high energy particles, known as cosmic rays, which originate from somewhere far out in space. And these are not just mildly energetic like we produce on Earth in particle accelerators, but many orders of magnitude more energetic than anything scientists can produce. But the source of these particles has been an unknown in astrophysics, with only a variety of theories to explain their origin.

However today the Large Area Telescope (LAT) onboard NASA's Fermi satellite made a discovery that could explain some of the cosmic rays. The astrophysicists working on this experiment have analyzed the data it as been returning on the energy and direction of gamma-rays and cosmic rays, and have found a significant number originating inside the constellation known as Cygnus. The origin appears to be a large bubble of gases, almost 160 lightyears long, which is generating new stars and such out of the debris of past supernovae. 

Of course the exact method by which these cosmic rays accelerate to such high energies can still only be speculated on. One leading theory is that the shockwave produced by past supernovae or by the bubble itself could be accelerating them, but more data and better models will be needed before that can be confirmed.

Still it is an interesting discovery, and a step forward for the study of cosmic rays and their origins.