sun-spot

sunspot

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

Origin:
1805–15; sun + spot

sunspotted, adjective
sunspottedness, noun
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Collins
World English Dictionary
sunspot (ˈsʌnˌspɒt)
 
n
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.  (Austral) a small cancerous spot produced by overexposure to the sun
 
'sunspotted
 
adj

Collins English Dictionary - Complete & Unabridged 10th Edition
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American Heritage
Science Dictionary
sunspot   (sŭn'spŏt')  Pronunciation Key 
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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