Cosmic rays--subatomic particles that zip across space at nearly the speed of light--rain down on Earth’s atmosphere all the time. The sun produces some of these particles, but most come from beyond the solar system. No one knows exactly from where, though, because magnetic fields in space warp the paths of the charged particles, making it hard to trace them to any particular source. But after decades of searching, astronomers have finally found solid evidence that exploding stars, or supernovas, are at least one source of cosmic rays.
Supernovas have actually been prime suspects all along. The shock waves created by a supernova explosion, astronomers theorized, could generate enormous magnetic fields capable of accelerating electrons, protons, and other ions to nearly the speed of light. But detecting this acceleration has proved very difficult. The accelerated particles should emit X-rays--but Earth’s atmosphere blocks those, making satellite observations necessary. Moreover, the radiation ...
