Solar energetic particles

Solar energetic particles (SEP) are high-energy particles coming from the Sun. They were first observed in the early 1940s. They consist of protons, electrons and HZE ions with energy ranging from a few tens of keV to GeV (the fastest particles can reach 80% of the speed of light). They are of particular interest and importance because they can endanger life in outer space (especially particles above 40 MeV).