born Oct. 25, 1789, Dessau, Anhalt died April 11, 1875, Dessau
Aspects of this topic are discussed in the following places at Britannica.
Although sunspots were known as early as 1600, no one noticed that their number changed with time until the German amateur astronomer Samuel Heinrich Schwabe announced the 11-year cycle in 1843. The 22-year magnetic cycle was discovered in 1925 by the American astronomer George Ellery Hale. Since that time, unsuccessful attempts have been made to connect the solar cycle to a variety of other...
in sunspot )...of the reality of these apparent flaws in the Sun came only about 1611, when systematic study was begun independently by Galileo, Thomas Harriot, Johannes Fabricius, and Christoph Scheiner. S.H. Schwabe in 1843 announced discovery of the solar cycle, in which the number of spots reaches a maximum about every 11 years on the average, as do the effects of solar disturbances (e.g.,...
in Sun: History of observation )
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