Observed cosmic rays may have come from two-million-year-old supernova

(Phys.org)—High-energy protons, nuclei, and other particles are constantly showering down on Earth's atmosphere from space, but the origins of these cosmic rays is unknown. One possibility is that the cosmic rays come from supernovae, although the evidence for this claim is limited. Now by analyzing the cosmic ray energy spectrum, scientists have been able to deduce that some high-energy cosmic rays may have originated from a two-million-year-old supernova located roughly 100 trillion mile