sunspot

n. relatively cool region which appears as a dark spot on the sun; summer resort (Slang)

A sunspot is a region on the Sun's surface (photosphere) that is marked by a lower temperature than its surroundings and has intense magnetic activity, which inhibits convection, forming areas of low surface temperature. Although they are blindingly bright at temperatures of roughly 4000-4500 K, the contrast with the surrounding material at about 5800 K leaves them clearly visible as dark spots. If they were isolated from the surrounding photosphere they would be brighter than an  electric arc. A minimum in the eleven-year sunspot cycle is predicted for 2007 [1]. Sunspots are often related to intense magnetic activity such as coronal loops and reconnection. Most solar flares and coronal mass ejections originate in magnetically active regions around sunspot groupings. Similar phenomena observed on stars other than the Sun are commonly called starspots.
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Noun
1. a cooler darker spot appearing periodically on the sun's photosphere; associated with a strong magnetic field
(synonym) macula
(hypernym) topographic point, place, spot

In the photosphere, i.e. , visible disk of the Sun, a dark marking that manifests a magnetic anomaly that is associated with interference with radio communications on Earth. Note: Sunspot activity, i.e. , the number of sunspots occurring at a given time or on a given day, is cyclic. The period of a cycle, from maximum through minimum and back to maximum sunspot count, is approximately 11 years.

A temporarily cooler region on the photosphere of the Sun. The temperature is typically between one and two thousand degrees below that of the photosphere, which is approximately 6000 Kelvin. A sunspot is thought to be caused by a magnetic field bursting through the photosphere and they will often appear in pairs or groups. In a pair, one spot will have north magnetic polarity and the other south. The spots migrate though latitudes, gradually getting closer to the equator, as the solar cycle progresses.