cosmic rays

British  

plural noun

1. Also called: cosmic radiation.  radiation consisting of particles, esp protons, of very high energy that reach the earth from outer space

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cosmic rays Cultural  

1. Elementary particles, mainly protons, that are produced by the sun and other stars and then strike the upper atmosphere of the Earth. Some of these particles are absorbed, some help form the Van Allen belt, and some reach the Earth's surface, where they form a part of the background radiation that constantly surrounds us.

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Example Sentences

A photography student at a university has created unique works of art using cosmic rays high above the earth.

From BBC • Apr. 29, 2026

Earth's magnetosphere offers some protection against radioactive cosmic rays and solar particles to the orbiting ISS, but no such cover on the Moon.

From Barron's • Apr. 10, 2026

The visionaries of the early Space Age didn’t worry much about solar radiation, coronal mass ejections, galactic cosmic rays, psychological stress from isolation, and cost-benefit ratios.

From Slate • Dec. 9, 2025

New work from astrophysicists at Michigan State University may help resolve a scientific question that has lingered for more than a century: where do galactic cosmic rays come from?

From Science Daily • Nov. 26, 2025

This query bore the unmistakable fingerprints of Arthur Compton, who reigned as the world’s leading expert on cosmic rays.

From "Big Science" by Michael Hiltzik