[suhn-spot] 
| one of the relatively dark patches that appear periodically on the surface of the sun and affect terrestrial magnetism and certain other terrestrial phenomena. |
| sun·spot (sŭn'spŏt') n. Any of the relatively cool dark spots appearing periodically in groups on the surface of the sun that are associated with strong magnetic fields. |
| 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. |
