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A Spotless Sun
Our sun is as spotless as a newborn Dalmatian! In the year 2008, the sun had the least number of sunspots in nearly a century--it went 266 out of 366 days with no spots. The last time the sun had such a low population of sunspots occurred in 1913, when there was no activity on 311 days of the year. And 2009 does not yet appear to be a promising year for sunspots either: as of March 31, no sunspots were visible on 78 out of 90 days, which is 87 percent.
A sunspot is a relatively cool area on the sun's surface, or photosphere, which appears as a black spot and lasts for about two weeks. The earliest record of sunspots originates from China in 28 BC, although it was very hard for astronomers to view the sun without the telescopes and light filters that we have today. Sunspots range in temperature from 4,000 to 4,500 Kelvin, and they can be as big as 50,000 miles in diameter. They are responsible for solar flares and high levels of ultraviolet radiation, caused by the spots' intense magnetic fields. Thus, the decreased number of sunspots is good for earth's atmosphere, which is constantly battered by the sun's radiation.
The sunspots follow an eleven year cycle, as noted by the eighteenth-century German astronomer Heinrich Schwabe, where activity wanes approximately every eleventh year. Accordingly, this period of infrequent sunspots is right on schedule, and scientists expect sunspot activity to increase again by the end of 2009.
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