A highly energetic atomic nucleus or other particle travelling through space at a speed approaching that of light.
More example sentences
- This radioactive isotope is created when energetic particles in cosmic rays enter the Earth's atmosphere and split atomic nuclei of nitrogen and oxygen.
- Other sources that contribute to the near-Earth space environment include galactic cosmic ray particles, which originate from outside of the solar system.
- The Moon's regolith was created by the ceaseless bombardment of micrometeorites, cosmic rays and particles of solar wind breaking down rocks for billions of years.
Definition of cosmic ray in:
- The US English dictionary