Astronomers have discovered a key fact required to understand the Sun's 11-year cycle of activity. Sunspots and flares on the Sun's surface follow the cycle, but expelled gas clouds do not. It seems that these ejections trail the sunspot peak - they peaked in 2002, two years after sunspots. The expelled gas takes away the Sun's old magnetic skin allowing a new one to emerge to start a new cycle. The Sun's 11-year cycle of activity - as recognised by the coming and going of sunspots - has been known since 1843, when Heinrich Schwabe, a German astronomer, noticed the pattern. Years later the activity was recognised as being of magnetic origin by George Ellery Hale, the American astronomer, who, in 1908, saw that sunspots were intensely magnetic. Since then many theories have been put forward to explain the solar rhythm. The accepted theory is that the sunspot cycle is a consequence of rotation and convection inside the Sun. The fact that the Sun's outer layers are bubbling, and that the Sun rotates faster at the equator than the poles, and faster on the inside than on the surface, results in a solar dynamo that, over 11 years, becomes increasingly wound up. So at some stage during the magnetic cycle the Sun has to somehow shed its old, contorted magnetic skin, and allow a newer, less troubled one, to emerge.
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