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 His fourth and final mission, STS-134, marked the last flight of Endeavour and delivered the Alpha Magnetic Spectrometer, a cosmic ray detector, to be mounted to the station's backbone truss. Robert Z. Pearlman, Scientific American, "Mark Kelly Becomes 4th Astronaut Elected to Congress," 6 Nov. 2020 The team measured the remnants from cosmic ray protons hitting silicon carbide molecules and breaking the silicon atoms into different components. Jay Bennett, Smithsonian Magazine, "Meteorite Grains Are the Oldest Known Solid Material on Earth," 13 Jan. 2020 In the future, Heck and others will isolate more presolar grains from meteorites such as Murchison and continue to date them using the cosmic ray technique. Jay Bennett, Smithsonian Magazine, "Meteorite Grains Are the Oldest Known Solid Material on Earth," 13 Jan. 2020 The methane molecules in older fossil fuel sources contain almost no carbon-14, a radioactive isotope of carbon created by cosmic ray bombardment. Warren Cornwall, Science | AAAS, "Humans are a bigger source of climate-altering methane, new studies suggest," 20 Feb. 2020 So, from the gamma ray telescope's perspective, the moon becomes a nifty detector for cosmic ray particles. Lauren Kent, CNN, "Why the moon glows brighter than the sun in these new NASA images," 16 Aug. 2019 Before the era of nuclear testing, carbon 14 was generated outside of labs only by cosmic rays falling from space. Carl Zimmer, The Atlantic, "Nuclear Tests Marked Life on Earth With a Radioactive Spike," 20 Mar. 2020 At least two comet-like objects have made their way to our solar system, and naked cores of atoms rain down upon our heads daily in the form of cosmic rays. Charlie Wood, Popular Science, "Ancient supernovas may have pierced moon rocks with star shrapnel," 30 Apr. 2020 Methanol could be on the surface of Arrokoth as a result of several possibilities, including a mixture of water and methane ice that was exposed to radiation via the sun's cosmic rays. Ashley Strickland, CNN, "Distant object in our solar system could show how planets form, scientists reveal," 13 Feb. 2020

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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The first known use of cosmic ray was in 1925

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Cite this Entry

“Cosmic ray.” Dictionary, Merriam-Webster, Accessed 21 Jan. 2021.

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More Definitions for cosmic ray

cosmic ray


English Language Learners Definition of cosmic ray

technical : 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

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