cosmic ray

noun

, Physics.

1. a radiation of high penetrating power that originates in outer space and consists partly of high-energy atomic nuclei.

cosmic ray

1. A ray of radiation of extraterrestrial origin, consisting of one or more charged particles such as protons, alpha particles, and larger atomic nuclei. Cosmic rays entering the atmosphere collide with atoms, producing secondary radiation, such as pions, muons, electrons, and gamma rays. Cosmic rays (and secondary radiation) can be easily seen in a cloud chamber.

Word History and Origins

Origin of cosmic ray¹

An Americanism dating back to 1920–25

Example Sentences

Tracking lines arc through the expansive field, recalling cosmic rays shooting across a cloud chamber.

From Los Angeles Times

Inspired by his doctoral adviser, John A. Simpson, Dr. Stone performed his first cosmic ray experiments in 1961 while working on Discover 36, an Air Force spy satellite.

From New York Times

Now that the spacecraft is outside the Sun’s protective bubble, its electronics are also vulnerable to strikes from galactic cosmic rays, charged particles accelerated to ultrahigh energies by supernovae and other cosmic engines.

From Science Magazine

She says lab experiments will now be needed to pin down exactly how DMS forms in space, where ultraviolet light and cosmic rays can power the synthesis of complex organic molecules.

From Science Magazine

Trillions of trillions of cosmic rays collide with Earth's atmosphere every day.

From Science Daily