By Ron Cowen
When it comes to revving up subatomic particles, the heavens leave the biggest particle accelerator on Earth in the dust. Our galaxy abounds with charged particles carrying energies that are thousands to millions of times as high as those that the most powerful atom smashers can muster. Known as cosmic rays, the particles–mostly protons–heat and ionize the interstellar medium, profoundly altering its chemical composition.
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Two reports this week shed light on the longstanding mystery of where these particles come from.