facula

[fak-yuh-luh]
noun, plural faculae [fak-yuh-lee] . Astronomy.
an irregular, unusually bright patch on the sun's surface.

Origin:
1700–10; < Latin: little torch, equivalent to fac- (stem of fax) torch + -ula -ule

facular, adjective
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World English Dictionary
facula (ˈfækjʊlə)
 
n , pl -lae
any of the bright areas on the sun's surface, usually appearing just before a sunspot and subject to the same 11-year cycle
 
[C18: from Latin: little torch, from fax torch]
 
'facular
 
adj

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American Heritage
Science Dictionary
facula   (fāk'yə-lə)  Pronunciation Key 
Plural faculae (fāk'yə-lē')
A bright, cloudlike structure on the Sun's surface, ascending several hundred kilometers above the photosphere and often associated with sunspots. Faculae are formed when a strong magnetic field heats a region of the photosphere to higher temperatures than the surrounding area. They occur all over the Sun but are usually only visible near the limb (the outer edge of the Sun's apparent disk), where the photosphere appears dimmer than in the center.
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Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Britannica
Encyclopedia

facula

in astronomy, bright granular structure on the Sun's surface that is slightly hotter or cooler than the surrounding photosphere. A sunspot always has an associated facula, though faculae may exist apart from such spots. Faculae are visible in ordinary white light near the Sun's limb (apparent edge), where the photospheric background is dimmer than near the centre of the disk. The extensions of faculae up into the chromosphere become visible over the entire disk in spectroheliograms taken at the wavelengths of hydrogen or ionized calcium vapour. When seen thus away from the limb, they are called chromospheric faculae or plages.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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Example sentences
The sunspot at lower left and the nearby bright facula close to the limb were especially prominent.
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