(Reuters) - A trio of top solar scientists said on Wednesday they had solved the mystery behind the disappearance of sunspots, a phenomenon that has stumped astrophysicists worldwide for more than two centuries. The research, which will be published on Thursday in the journal Nature, shows that unusually weak magnetic fields on the sun paired with reduced solar activity cause sunspots to disappear. Sunspots appear to the human eye as dark spots on the sun, some as wide as 49,000 miles, according to NASA. They are caused by intense magnetic activity, or storms, on the sun's surface, which is plasma. Sunspots often emit particles into space which are known as solar flares. Sunspots went missing from 2008 to 2010 in a rare occurrence that first was reported in 1810. Although it is well documented that the sun goes through regular 11-year cycles of high and low solar activity, sunspots are not prone to disappear for an extended period, the researchers said. "Understanding su...