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A solar energetic particle (SEP) is a solar particle with a kinetic energy of tens of keV or greater, potentially more than a GeV, moving at relativistic speed. (Solar particles are protons, electrons, helium ions and or HZE ions from the Sun.) SEPs are associated with strong coronal mass ejections (CMEs), and are the danger that space weather presents to humans and spacecraft (the particles are identical to those from something dangerously radioactive). The term solar cosmic ray (SCR) essentially means the same thing. Often, 10 GeV is used as an upper threshold above which the particle can be presumed to be from beyond the solar system, thus a galactic cosmic ray (GCR). Normal (non SEP) solar wind particles generally have kinetic energy in the 0-10 keV range.