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sunspot

[suhn-spot]
noun
  1. one of the relatively dark patches that appear periodically on the surface of the sun and affect terrestrial magnetism and certain other terrestrial phenomena.
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Origin of sunspot

First recorded in 1805–15; sun + spot
Related formssun·spot·ted, adjectivesun·spot·ted·ness, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for sunspot

Contemporary Examples of sunspot

Historical Examples of sunspot

  • A sunspot is a region on the Sun that is cooler than its surroundings.

    Disturbing Sun

    Robert Shirley Richardson

  • Also the present sunspot cycle started its rise to maximum about 1954.

    Disturbing Sun

    Robert Shirley Richardson

  • Because the average period of solar rotation in the sunspot zone is not twenty-seven days but twenty-seven point three days.

    Disturbing Sun

    Robert Shirley Richardson

  • They are connected in this way: that sunspot activity and S-Region activity certainly go together.

    Disturbing Sun

    Robert Shirley Richardson

  • Sunspot activity continues at a high level and is steadily mounting in violence.

    Disturbing Sun

    Robert Shirley Richardson


British Dictionary definitions for sunspot

sunspot

noun
  1. any of the dark cool patches, with a diameter of up to several thousand kilometres, that appear on the surface of the sun and last about a week. They occur in approximately 11-year cycles and possess a strong magnetic field
  2. informal a sunny holiday resort
  3. Australian a small cancerous spot produced by overexposure to the sun
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Derived Formssunspotted, adjective
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for sunspot

n.

1868, in astronomy, from sun (n.) + spot (n.). Earlier "a spot on the skin caused by exposure to the sun" (1818).

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Online Etymology Dictionary, © 2010 Douglas Harper

sunspot in Science

sunspot

[sŭnspŏt′]
  1. Any of the dark, irregular spots that usually appear in groups on the surface of the Sun (its photosphere), lasting from a few days to several weeks or more. Sunspots appear dark because they are cooler, by up to 1,500°K, than the surrounding photosphere. They are associated with strong magnetic fields and solar magnetic storms moving in a vortex pattern, similar to a tornado on Earth. The number of sunspots waxes and wanes over an 11-year period; at maximum activity there are often increased numbers of solar flares.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.