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sunspots
Dark, irregular areas on the solar surface with strong magnetic fields (1000 to 2000 Gauss) surrounded by gray zones (penumbra). Sunspots occur mostly in pairs, with opposite magnetic polarity; they persist for periods of days, weeks, or months. Their temperatures are about 2000 K lower than the temperature of the surrounding photosphere (5780 K). The frequency of sunspots follows an eleven-year cycle.





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