caption doctoral_advisor death_date birth_place image_size nationality field work_institutions birth_date known_for image article_title name alma_mater
rudolf wolf encke 6 december 1893 fällanden 150px switzerland astronomer university of zurich 7 july 1816 sunspots rudolf wolf.jpg rudolf wolf
 rudolf wolf university of zurich
rudolf wolf

johann rudolf wolf -lrb- 7 july 1816 -- 6 december 1893 -rrb- was a swiss astronomer and mathematician best known for his research on sunspots .
wolf was born in fällanden , near zurich .
he studied at the universities of zurich , vienna , and berlin .
encke was one of his teachers .
wolf became professor of astronomy at the university of bern in 1844 and director of the bern observatory in 1847 .
in 1855 he accepted a chair of astronomy at both the university of zurich and the federal institute of technology in zurich .
wolf was greatly impressed by the discovery of the sunspot cycle by heinrich schwabe and he not only carried out his own observations , but he collected all the available data on sunspot activity back as far as 1610 and calculated a period for the cycle of 11.1 years .
in 1848 he devised a way of quantifying sunspot activity .
the wolf number , as it is now called , remains in use .
in 1852 wolf was one of four people who discovered the link between the cycle and geomagnetic activity on earth .
