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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
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. 2015.
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Examples from the web for photosphere
  • These particles came from the sun's visible surface, called the photosphere.
  • The sunspots are darker, deeper, and cooler than the photosphere.
  • The photosphere is the visible surface of the sun and the lowest layer of the atmosphere.
  • The center does not radiate in space so it is irrelevant, likewise everything below the photosphere.
  • The tops of convective cells can be seen on the photosphere as granules.
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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