Person: Wolf, Johann Rudolf
Rudolf Wolf was a Swiss astronomer and mathematician best known for his research on sunspots.
Mathematical Profile (Excerpt):
- After studying at the Zürich Industrieschule, Wolf attended the University of Zürich where he was taught by Raabe and Gräffe.
- Wolf became director of the Bern Observatory in 1847.
- An observatory was opened at Zürich in 1864, largely due to Wolf's efforts, and he was appointed as director.
- Wolf wrote on prime number theory and geometry, then later on probability and statistics - a series of papers discussed Buffon's needle experiment in which he estimated π by Monte Carlo methods.
- First, however, we discuss Wolf's main contribution which was his study of the 11 year sunspot cycle.
- Wolf, who at that time was in Bern, was fascinated and in 1847 he began his own observational record of sunspots.
- In the following year he devised a system which is now known as 'Wolf's sunspot numbers'.
- Of course an 11 year cycle requires considerable data and Wolf collected not only current data, but data from historic records from 1610 onwards.
- From this data Wolf was the first to calculate an accurate length of the cycle, obtaining a value of 11.1 years.
- Wolf's findings were not well received by his fellow astronomers who argued strongly against his conclusions.
- However Wolf was totally convinced of his discoveries and the validity of his methods, and of course we know that he was right to remain so.
- Wolf conducted experiments throwing the needle 5000 times, obtaining a value of to be 3.1596.
- However, more interestingly, Wolf wanted to show that the method of least squares could be used to estimate the error.
- In this respect, Wolf's paper can be called a forerunner of the Monte Carlo method.
- It is likely that only after 1884 was Wolf aware of the history of the problem, and that Buffon was the first to propose it.
- Wolf also made significant contributions to the history of science.
Born 7 July 1816, Fällanden (near Zürich), Switzerland. Died 6 December 1893, Zürich, Switzerland.
View full biography at MacTutor
Tags relevant for this person:
Astronomy, Origin Switzerland
Thank you to the contributors under CC BY-SA 4.0! 
- Github:
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- non-Github:
- @J-J-O'Connor
- @E-F-Robertson
References
Adapted from other CC BY-SA 4.0 Sources:
- O’Connor, John J; Robertson, Edmund F: MacTutor History of Mathematics Archive
