cosmic radiation

streams of highly penetrating charged particles bombarding the earth from outer space

Cosmic rays are energetic particles originating from space that impinge on Earth's atmosphere. Almost 90% of all the incoming cosmic ray particles are protons, about 9 re helium nuclei (alpha particles) and about 1 re electrons. The term "ray" is a misnomer, as cosmic particles arrive individually, not in the form of a ray or beam of particles.
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Penetrating ionizing radiation, both particulate and electromagnetic, originating in outer space. Secondary cosmic rays, formed by interactions in the Earth's atmosphere, account for about 45 to 50 millirem of the 360 millirem background radiation that an average individual receives in a year.

Noun
1. radiation consisting of cosmic rays
(hypernym) radiation
(hyponym) cosmic background radiation, CBR, cosmic microwave background radiation, CMBR, cosmic microwave background, CMB
(part-meronym) cosmic ray