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
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Recent Examples of cosmic ray from the Web
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The solar and cosmic rays strip atoms in the area of one or more of their electrons, giving them a positive charge and leaving the electrons to act as free particles.
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Despite its strange shape, trajectory and lack of a tail, ‘Oumuamua is just a comet after all, its ice locked away beneath a tarlike crust hardened and desiccated by eons of bombardment by cosmic rays.
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On Earth, a powerful magnetic field and the atmosphere largely protect humans (and Tesla Roadsters) from the harsh radiation of the sun and cosmic rays.
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By comparing the plasma density after both solar flare-ups and then extrapolating backwards, Gurnett's team concluded that Voyager 1 left the heliosphere in August 2012—which lines up with the cosmic ray changes.
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The satellite, which weighed less than 31 pounds, was equipped with instruments to measure cosmic rays.
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One explanation is that over many millennia cosmic rays have transformed the icy, volatile chemicals that would be expected to stream off a comet into more stable compounds.
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Space has no atmosphere to protect DNA from the Sun’s pummeling, destructive radiation; cosmic rays shoot out of deep space with no regard for the building blocks of life.
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Can the energy spectra of cosmic rays result from a single mechanism?
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.
First Known Use of cosmic ray
1925
COSMIC RAY Defined for English Language Learners
cosmic ray
Definition of cosmic ray for English Language Learners
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: a stream of energy that enters the Earth's atmosphere from outer space
COSMIC RAY Defined for Kids
cosmic ray
Definition of cosmic ray for Students
: a stream of very penetrating particles that enter the earth's atmosphere from outer space at high speed
Learn More about cosmic ray
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See words that rhyme with cosmic ray Britannica.com: Encyclopedia article about cosmic ray
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