Cosmic rays are rays that reach Earth from outer space and consist of atomic nuclei.
cosmic rays in British English
plural noun
radiation consisting of particles, esp protons, of very high energy that reach the earth from outer space
Also called: cosmic radiation
cosmic rays in American English
US
streams of high-energy charged particles from outer space, composed of protons, alpha particles, and a few heavier nuclei, which bombard the atoms in the upper atmosphere and produce various secondary nuclear particles which shower the earth
Examples of 'cosmic rays' in a sentence
cosmic rays
It serves the double purpose of filtering out cosmic rays and other nasty stuff, like micrometeorites.