- Jan 7, 2002
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(PhysOrg.com) -- Sunspot formation is triggered by a magnetic field, which scientists say is steadily declining. They predict that by 2016 there may be no remaining sunspots, and the sun may stay spotless for several decades. The last time the sunspots disappeared altogether was in the 17th and 18th century, and coincided with a lengthy cool period on the planet known as the Little Ice Age.
Sunspots are regions of electrically charged, superheated gas (plasma) on the surface of the sun, formed when upwellings of the magnetic field trap the ionized plasma. The magnetic field prevents the gas from releasing the heat and sinking back below the suns surface. These areas are somewhat cooler than the surrounding sun surface and so appear to us as dark spots.
Sunspots have been observed at least since the early 17th century, and they are known to follow an 11 year cycle from solar maximum to solar minimum. The solar minimum usually lasts around 16 months, but the current minimum has already lasted 26 months, which is the longest minimum in a hundred years.
http://www.physorg.com/news203746768.html