Tuesday, February 19, 2008

17th century solar oddity believed linked to global cooling is rare among nearby stars

A mysterious 17th century solar funk that some have linked to Europe’s Little Ice Age and to global climate change, becomes even more of an enigma as a result of new observations by University of California, Berkeley, astronomers. For 70 years, from 1645 until 1714, early astronomers reported almost no sunspot activity. The number of sunspots - cooler areas on the sun that appear dark against the brighter surroundings - dropped a thousandfold, according to some estimates. Though activity on the sun ebbs and flows today in an 11-year cycle, it has not been that quiet since. Since 1976, when it was pointed out that this lengthy period of low sunspot activity, the so-called Maunder minimum, coincided with the coldest part of the Little Ice Age in Europe and North America, astronomers have been searching nearby sun-like stars for examples of stellar minima. They have hoped to determine how common such minima are and to predict the next solar minimum - and perhaps the next period of global cooling.

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