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A solar energetic particle (SEP) is a proton, electron, helium ion or HZE ion (metal nucleus with no electron) from the Sun, with a kinetic energy of tens of keV or greater, potentially more than a GeV and with relativistic speed. They 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 are generally in the 0-10 keV range.