Rudolf Wolf Explained
Johann Rudolf Wolf (7 July 1816 – 6 December 1893) 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.[1] 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.[2] [3]
Around 1850, to study the laws of probability, Wolf performed a Buffon's needle experiment, dropping a needle on a plate 5000 times to verify the value of π, a precursor to the Monte Carlo method.[4] [5] [6]
References
- Wolf . R. . Neue Untersuchungen über die Periode der Sonnenflecken und ihre Bedeutung . Mittheilungen der Naturforschenden Gesellschaft in Bern . 1852 . 255 . 249–270 . New investigations regarding the period of sunspots and its significance . de. Wolf's estimates of the solar cycle's period appear on p. 250 and p. 251.
- Wolf . R. . Sonnenflecken-Beobachtungen in der ersten Hälfte des Jahres 1852; Entdeckung des Zusammenhanges zwischen den Declinationsvariationen der Magnetnadel und den Sonnenflecken . Mittheilungen der Naturforschenden Gesellschaft in Bern . 1852 . 245 . 179–184 . Sunspot observations in the first half of the year 1852; discovery of a relation between the variations of the declination of the magnetic needle and sunspots . de.
Notices of Wolf's discovery appeared in:
- The three other astronomers who observed a relation between the solar cycle and magnetic declination on Earth were:
- Johann von Lamont (1805–1879) of Scotland and Germany: Lamont . Ueber die zehnjährige Periode, welche sich in der Gröβe der täglichen Bewegung der Magnetnadel darstellt . Annalen der Physik . 1851 . 84 . 572–584 . 10.1002/andp.18511601206 . 2nd series . On the ten-year period which is present in the magnitude of the daily movement of the magnetic needle . de.
- Edward Sabine (1788–1883) of Ireland: Sabine . Edward . On the periodical laws discoverable in the mean effects of the larger magnetic disturbances . Philosophical Transactions of the Royal Society of London . 1852 . 142 . 103–124 . 10.1098/rstl.1852.0009. free . From p. 103: " … I have had the satisfaction of finding that the observations [of magnetic declination] of these years [i.e., 1846–1848] confirm … the existence of a periodical variation, which … corresponds precisely both in period and epoch, with the variation in the frequency and magnitude of the solar spots, recently announced by M. Schwabe … "
- Jean-Alfred Gautier (1793–1881) of Switzerland: Gautier . Alfred . Notice sur quelques recherches récentes, astronomiques et physiques, relative aux apparences que présente le corps du soleil . Archives des sciences physiques et naturelles . 1852 . 20 . 177–207, 265–282 . Notice on some recent astronomical and physical investigations regarding appearances that the body of the sun shows . fr. On pp. 189–190, after discussing Schwabe's discovery of the solar cycle, Gautier presents Lamont's findings on the relation between the solar cycle and the periodic variations in the magnetic declination. Gautier mentions that the Austrian astronomer Augustin Reslhuber (1808–1875) confirmed Lamont's findings. (Reslhuber's confirmation appeared in: Reslhuber . A. . Ueber die vom Dr. Lamont beobachtete zehn-jährige Periode in der Größe der täglichen Bewegung der Declinationsnadel . Annalen der Physik . 1852 . 85 . 412–420 . 10.1002/andp.18521610311 . 2nd series . On the ten-year period in the magnitude of the daily movement of the declination needle, which was observed by Dr. Lamont . de.)
- Web site: Wolf biography. www-history.mcs.st-andrews.ac.uk. 2017-10-20.
- Riedwyl. Hans. 1990. Rudolf Wolf's Contribution to the Buffon Needle Problem (an Early Monte Carlo Experiment) and Application of Least Squares. 2684154. The American Statistician. 44. 2. 138–139. 10.2307/2684154.
- Book: J.V. Uspensky. Introduction To Mathematical Probability. 1937. 112–113.
Further reading
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