Cosmic ray

High-energy particle, mainly originating outside the Solar System

Cosmic rays or astroparticles are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from outside the Solar System—from the Milky Way, from distant galaxies, and from the Sun. Upon impact with Earth's atmosphere, cosmic rays produce showers of secondary particles, some of which reach the surface, although the bulk are deflected into space by Earth's magnetic field (the magnetosphere) or by the heliosphere.

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