Charles-Eugène Delaunay
{{Short description|French astronomer and mathematician (1816–1872)}}
{{Infobox scientist
| name = Charles-Eugène Delaunay
| image = Charles Eugene Delaunay.jpeg
| image_size = 150px
| caption = Charles-Eugène Delaunay
| birth_date = {{Birth date|1816|4|9|df=y}}
| birth_place = Lusigny-sur-Barse, France
| death_date = {{death date and age|1872|8|5|1816|4|9|df=y}}
| death_place = Cherbourg, France
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| citizenship =
| nationality = French
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| field = Astronomy
Celestial mechanics
| work_institutions = Paris Observatory
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| known_for = Delaunay variables
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Charles-Eugène Delaunay ({{IPA|fr|ʃaʁl øʒɛn dəlonɛ}}; 9 April 1816 – 5 August 1872) was a French astronomer and mathematician. His lunar motion studies were important in advancing both the theory of planetary motion and mathematics.{{cite journal|title=Obituary: M. Charles E. Delaunay|journal=MNRAS|date=February 1873|volume=33|pages=203–209|bibcode=1873MNRAS..33..190.|url=http://babel.hathitrust.org/cgi/pt?id=mdp.39015065215124;view=1up;seq=227|doi = 10.1093/mnras/33.4.190 |doi-broken-date=1 November 2024|doi-access=free }}
Life
Born in Lusigny-sur-Barse, France, to Jacques-Hubert Delaunay and Catherine Choiselat,{{cite book |title=The Biographical Encyclopedia of Astronomers |last=Hockey |first=Thomas |year=2009 |publisher=Springer Publishing |isbn=978-0-387-31022-0 |access-date=August 22, 2012 |url=http://www.springerreference.com/docs/html/chapterdbid/58351.html}} Delaunay studied under Jean-Baptiste Biot at the Sorbonne. He worked on the mechanics of the Moon as a special case of the three-body problem. He published two volumes on the topic, each of 900 pages in length, in 1860 and 1867. The work hints at chaos in the system, and clearly demonstrates the problem of so-called "small denominators" in perturbation theory. His infinite series expression for finding the position of the Moon converged too slowly to be of practical use but was a catalyst in the development of functional analysisO'Connor & Edmund and computer algebra.R. Pavelle, M. Rothstein and J. Fitch, "Computer Algebra", Scientific American, 245 (6), pp.102-113 (December 1981)
Delaunay became director of the Paris Observatory in 1870 but drowned in a boating accident near Cherbourg, France, two years later. He was followed by Jean Claude Bouquet at the Academy. Peter Guthrie Tait in his book An Elementary Treatise on Quaternions edition 1867 on page 244 named Didonia in honour of Delaunay.
Honours
- Member of the Académie des Sciences, (1855)[Anon.] (2001)
- Gold Medal of the Royal Astronomical Society, (1870){{Citation
|url = http://www.ras.org.uk/images/stories/awards/winners/gold_medallists.pdf
|archive-url = https://web.archive.org/web/20150924084826/http://www.ras.org.uk/images/stories/awards/winners/gold_medallists.pdf
|url-status = dead
|archive-date = 24 September 2015
|title = Gold Medal Winners
|publisher = Royal Astronomical Society
|access-date = 4 November 2014
}}
- His name is one of the 72 names inscribed on the Eiffel Tower.
References
{{Reflist}}
Bibliography
=By Delaunay=
- {{ cite book | title=Cours élémentaire de mécanique | orig-year=1850 | author=Delaunay, C.-E. | year=1874 | edition=8th}}
- {{ cite book | title=Cours élémentaire d'astronomie | orig-year=1853 | edition=5th | year=1870 | author=Delaunay, C.-E.}}
- {{ cite book | title=Traité de mécanique rationnelle | orig-year=1856 | author=Delaunay, C.-E. | edition=4th | year=1873}}
- {{ cite book | title=Théorie du mouvement de la lune | volume=1 | year=1860 | author=Delaunay, C.-E.}}
- {{ cite book | title=Théorie du mouvement de la lune | volume=2 | year=1867 | author=Delaunay, C.-E.}}
- {{ cite book | title=Ralentissement de la rotation de la terre | year=1866 | author=Delaunay, C.-E.}}
- {{ cite book | title=Rapport sur les progrès de l'astronomie | year=1867 | author=Delaunay, C.-E.}}
=About Delaunay=
- [Anon.] (2001) "Delaunay, Charles-Eugène", ''Encyclopædia Britannica, Deluxe edition CD-ROM
- {{MacTutor Biography|id=Delaunay}}
- [https://bibnum.obspm.fr/ark:/11287/3Jj6M Some of Delaunay's works are digitalized] on Paris Observatory digital library.
{{Authority control}}
{{DEFAULTSORT:Delaunay, Charles-Eugene}}
Category:École Polytechnique alumni
Category:Mines Paris - PSL alumni
Category:19th-century French astronomers
Category:19th-century French mathematicians
Category:Recipients of the Gold Medal of the Royal Astronomical Society
Category:Foreign members of the Royal Society
Category:Members of the French Academy of Sciences