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Solar Nap

April 30, 2015

300 years ago, the Sun woke up from a lengthy “nap.” For seven decades, almost no sunspots had marred its surface. That hasn’t happened since, but it’s almost certain to happen again.

Sunspots are dark magnetic storms. Their number typically waxes and wanes over a period of about 11 years. At the peak of this cycle, there may be hundreds of sunspots at a time.

But from 1645 to 1715, the Sun’s surface remained almost unblemished. In some of those years — a period known as the Maunder Minimum — astronomers recorded no sunspots at all.

No one knows why the Sun became so docile. But evidence gathered from tree rings and ice cores, as well as observations of stars that are similar to the Sun, suggest that it happens every few centuries.

That’s particularly intriguing because the Maunder Minimum coincided with the coldest part of the Little Ice Age — a time when parts of Europe, North America, and other regions were especially frigid. The lack of sunspots may have corresponded with a tiny drop in the Sun’s total energy output, which combined with other factors to chill our planet by a degree or so.

The current sunspot cycle, which peaked a year ago, is the weakest in more than a century. And some scientists predict that the next one could be weaker still. In fact, some have even speculated that we could be heading into a new Maunder Minimum. And even if we’re not, there’s little doubt that the Sun eventually will nod off for another long nap.


Script by Damond Benningfield, Copyright 2015

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