cosmic ray


Definition of cosmic ray 

: a stream of atomic nuclei of extremely penetrating character that enter the earth's atmosphere from outer space at speeds approaching that of light

Examples of cosmic ray in a Sentence

Recent Examples on the Web

The key fact here is that cosmic rays can’t penetrate ice. Avery Thompson, Popular Mechanics, "Antarctica's Ice May Be More Durable Than We Thought," 13 June 2018 Known as ultrahigh-energy cosmic rays, these particles have a million times more energy than has ever been produced in an earthbound particle accelerator, but what boosts them to such colossal energies is unknown. Daniel Clery, Science | AAAS, "Ghostly particle caught in polar ice ushers in new way to look at the universe," 12 July 2018 The passengers included the Mikhailo Lomonosov satellite, named after the prolific 18-century Russian scientist and intended for probing cosmic rays and their interaction with the Earth's atmosphere. Anatoly Zak, Popular Mechanics, "Why Putin Wouldn't Let You Watch Russia's Latest Space Launch," 28 Apr. 2016 The identification of blazars as a likely source for cosmic rays rounds out a story that began with one of the most daring discoveries in all of physics. Mark Johnson, Milwaukee Journal Sentinel, "Blazing a trail: UW professor's dream leads to breakthrough in identifying origin of cosmic rays," 12 July 2018 But unlike neutrinos, cosmic rays have a charge, which means their path can be deflected by magnetic fields. Author: Sarah Kaplan, Anchorage Daily News, "In a cosmic first, scientists detect ‘ghost particles’ from a distant galaxy," 12 July 2018 Astronomers have wondered about this since cosmic rays were first discovered, way back in 1912. Mike Wall, NBC News, "High-energy 'ghost particle' traced to distant galaxy in astronomy breakthrough," 12 July 2018 Most of the neutrinos detected by IceCube originated nearby, spawned by cosmic rays hitting Earth's upper atmosphere. Daniel Clery, Science | AAAS, "Ghostly particle caught in polar ice ushers in new way to look at the universe," 12 July 2018 Thursday's announcement that a likely source of cosmic rays has been discovered by an observatory at the South Pole is only the most recent breakthrough to feature UW researchers. Mark Johnson, Milwaukee Journal Sentinel, "UW scientific advances include vitamins, growing human embryonic stem cells in lab," 12 July 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'cosmic ray.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of cosmic ray

1925, in the meaning defined above

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Last Updated

11 Oct 2018

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Time Traveler for cosmic ray

The first known use of cosmic ray was in 1925

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More Definitions for cosmic ray

cosmic ray


English Language Learners Definition of cosmic ray

: a stream of energy that enters the Earth's atmosphere from outer space

cosmic ray


Kids Definition of cosmic ray

: a stream of very penetrating particles that enter the earth's atmosphere from outer space at high speed

More from Merriam-Webster on cosmic ray

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Comments on cosmic ray

What made you want to look up cosmic ray? Please tell us where you read or heard it (including the quote, if possible).


exaggeratedly or childishly emotional

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