Sunspot

A sunspot is a region on the Sun's surface (photosphere) that is marked by a lower temperature than its surroundings, and intense magnetic activity. Although they are blindingly bright, at temperatures of roughly 5000 K, the contrast with the surrounding material at some 6000 K leaves them clearly visible as dark spots. If they were isolated from the surrounding photosphere they would be brighter than an electric arc.

References

• {{Journal reference issue | Author=Solanki, S.K., I.G. Usoskin, B. Kromer, M. Schussler and J. Beer | Title=Unusual activity of the Sun during recent decades compared to the previous 11,000 years | Journal=Nature | Volume=431 | Issue=7012 | Year=2004 | Pages=1084-1087}} {{doi|10.1038/nature02995}} {{Web reference | title=11,000 Year Sunspot Number Reconstruction | work=Global Change Master Directory | URL=http://gcmd.nasa.gov/KeywordSearch/Metadata.do?Portal=GCMD&KeywordPath=%5BParameters%3ACategory%3D%27EARTH+SCIENCE%27%2CTopic%3D%27SUN-EARTH+INTERACTIONS%27%2CTerm%3D%27SOLAR+ACTIVITY%27%2CVariable%3D%27SUNSPOTS%27%5D&OrigMetadataNode=GCMD&EntryId=NOAA_NCDC_PALEO_2005-015&MetadataView=Brief&MetadataType=0&lbnode=gcmd3b | date=11 March | year=2005}}