Johann Rudolf Wolf (7 July 1816 – 6 December 1893) was a

Swiss Swiss may refer to: * the adjectival form of Switzerland * Swiss people Places * Swiss, Missouri * Swiss, North Carolina *Swiss, West Virginia * Swiss, Wisconsin Other uses *Swiss-system tournament, in various games and sports *Swiss Internation ...

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...

and

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change. History On ...

best known for his research on

sunspot Sunspots are phenomena on the Sun's photosphere that appear as temporary spots that are darker than the surrounding areas. They are regions of reduced surface temperature caused by concentrations of magnetic flux that inhibit convection. Sun ...

s. Wolf was born in

Fällanden Fällanden is a municipality in the district of Uster in the canton of Zürich in Switzerland, and belongs to the Glatt Valley (German: ''Glattal''). History Fällanden is first mentioned around 820 as ''Fenichlanda''. Geography Fällande ...

, near Zurich. He studied at the universities of Zurich, Vienna, and Berlin.

Encke Encke may refer to: *Johann Franz Encke (1791–1865), a nineteenth-century German astronomer ** Encke (crater), a lunar crater ** Encke Division, a dark gap in the rings of Saturn **Comet Encke, a short-period comet ***Encke (horse) (2009–2014) ...

was one of his teachers. Wolf became professor of astronomy at the

University of Bern The University of Bern (german: Universität Bern, french: Université de Berne, la, Universitas Bernensis) is a university in the Switzerland, Swiss capital of Bern and was founded in 1834. It is regulated and financed by the Canton of Bern. It ...

in 1844 and director of the Bern Observatory in 1847. In 1855 he accepted a chair of astronomy at both the

University of Zurich The University of Zürich (UZH, german: Universität Zürich) is a public research university located in the city of Zürich, Switzerland. It is the largest university in Switzerland, with its 28,000 enrolled students. It was founded in 1833 f ...

and the

Federal Institute of Technology (colloquially) , former_name = eidgenössische polytechnische Schule , image = ETHZ.JPG , image_size = , established = , type = Public , budget = CHF 1.896 billion (2021) , rector = Günther Dissertori , president = Joël Mesot , a ...

in Zurich. Wolf was greatly impressed by the discovery of the sunspot cycle by

Heinrich Schwabe Samuel Heinrich Schwabe (25 October 1789 – 11 April 1875) a German astronomer remembered for his work on sunspots. Schwabe was born at Dessau. At first an apothecary, he turned his attention to astronomy, and in 1826 commenced his observatio ...

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 The Wolf number (also known as the relative sunspot number or Zürich number) is a quantity that measures the number of sunspots and groups of sunspots present on the surface of the Sun. History Astronomers have been observing the Sun recordi ...

, 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. Around 1850, to study the laws of probability, Wolf performed a

Buffon's needle In mathematics, Buffon's needle problem is a question first posed in the 18th century by Georges-Louis Leclerc, Comte de Buffon: :Suppose we have a floor made of parallel strips of wood, each the same width, and we drop a needle onto the floor. ...

experiment, dropping a needle on a plate 5000 times to verify the value of π, a precursor to the

Monte Carlo method Monte Carlo methods, or Monte Carlo experiments, are a broad class of computational algorithms that rely on repeated random sampling to obtain numerical results. The underlying concept is to use randomness to solve problems that might be determi ...

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External links

HAO "Rudolf Wolf (1816–1893"

Analysis of Wolf's dice data
by

Edwin Jaynes Edwin Thompson Jaynes (July 5, 1922 – April 30, 1998) was the Wayman Crow Distinguished Professor of Physics at Washington University in St. Louis. He wrote extensively on statistical mechanics and on foundations of probability and statisti ...

19th-century Swiss astronomers 1816 births 1893 deaths Historians of astronomy University of Zurich alumni University of Zurich faculty ETH Zurich faculty Members of the French Academy of Sciences {{Mathematician-stub

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