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[foh-tuh-sfeer] /ˈfoʊ təˌsfɪər/
a sphere of light or radiance.
Astronomy. the luminous visible surface of the sun, being a shallow layer of strongly ionized gases.
Origin of photosphere
First recorded in 1655-65; photo- + -sphere
Related forms
[foh-tuh-sfer-ik, -sfeer-] /ˌfoʊ təˈsfɛr ɪk, -ˈsfɪər-/ (Show IPA),
adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2017.
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Examples from the Web for photosphere
Historical Examples
  • That part of the sun's surface under observation is known as the photosphere, that is, the part which radiates light.

    Astronomy David Todd
  • It is from the photosphere, as has been said, that we have won most of our knowledge of the sun.

  • They seem to shrink away as a consequence of the photosphere closing in upon them.

    Astronomy of To-day Cecil G. Dolmage
  • The part of the Sun that we see is its luminous surface, or photosphere.

    Astronomy for Amateurs Camille Flammarion
  • The systematic drift of the photosphere is strictly a drift in longitude; its direction is everywhere parallel to the equator.

  • Dark spots of a deep bluish black will often be seen on the photosphere of the sun.

    Astronomy David Todd
  • Of the more special appearances which the photosphere presents, let us take first the faculæ.

  • The maze of her hair could hardly be told from the photosphere.

    Lore of Proserpine Maurice Hewlett
  • This is a layer of relatively cool gases lying immediately upon the photosphere.

    Astronomy of To-day Cecil G. Dolmage
  • Beneath the chromosphere is the layer of the sun from which emanates the light by which we see it, called the photosphere.

    Astronomy David Todd
British Dictionary definitions for photosphere


the visible surface of the sun, several hundred kilometres thick
Derived Forms
photospheric (ˌfəʊtəʊˈsfɛrɪk) 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
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Word Origin and History for photosphere

1660s, "orb of light," from photo- + -sphere. Astronomical sense is from 1848.

Online Etymology Dictionary, © 2010 Douglas Harper
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photosphere in Science
The lowest visible layer of a star, lying beneath the chromosphere and the corona. Stars are made entirely of gas and thus have no surface per se, but the gas beneath the photosphere is opaque, so the photosphere acts as their effective visible surface; it is also the boundary from which the Sun's diameter is measured. The Sun's photosphere is a very thin layer made up of numerous granules (transient convective cells) where hot gases rise and give off light and heat. The photosphere of the Sun has a temperature of around 6,000°K and is the region in which sunspot activity is located.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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