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.
Note: The number of sunspots goes through a maximum and minimum about every eleven years. During periods of maximum sunspots, the elementary particles associated with the spots cause disturbances in the atmosphere of the Earth and interfere with radio and television communication.