Children's, Intermediate and Advanced Online English Dictionary & Thesaurus

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cosmic dust very fine particles of matter found in interplanetary space.
cosmic noise interference from radio waves beyond the earth; galactic noise.
cosmic ray high energy radiation, consisting primarily of high-energy protons and alpha particles, that primarily originates from outside the solar system. Upon collision with earth's atmosphere, secondary particles can be produced that sometimes reach the earth's surface.
cosmic rays streams of high-energy charged atomic nuclei or other particles that enter the earth's atmosphere from outer space.