Charles-Eugène Delaunay

Charles-Eugène Delaunay (French pronunciation: [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.

Life

Born in Lusigny-sur-Barse, France, to Jacques‐Hubert Delaunay and Catherine Choiselat, 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 analysis and computer algebra.

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)
• Gold Medal of the Royal Astronomical Society, (1870)
• His name is one of the 72 names inscribed on the Eiffel Tower.

References

Bibliography

By Delaunay

• Delaunay, C.-E. (1874) [1850]. Cours élémentaire de mécanique (8th ed.).
• Delaunay, C.-E. (1870) [1853]. Cours élémentaire d'astronomie (5th ed.).
• Delaunay, C.-E. (1873) [1856]. Traité de mécanique rationnelle (4th ed.).
• Delaunay, C.-E. (1860). Théorie du mouvement de la lune. Vol. 1.
• Delaunay, C.-E. (1867). Théorie du mouvement de la lune. Vol. 2.
• Delaunay, C.-E. (1866). Ralentissement de la rotation de la terre.
• Delaunay, C.-E. (1867). Rapport sur les progrès de l'astronomie.

About Delaunay

• [Anon.] (2001) "Delaunay, Charles-Eugène", Encyclopædia Britannica, Deluxe edition CD-ROM
• O'Connor, John J.; Robertson, Edmund F., "Charles-Eugène Delaunay", MacTutor History of Mathematics Archive, University of St Andrews
• Some of Delaunay's works are digitalized on Paris Observatory digital library.

1. Delaunay
2. Orbital elements
3. Delaunay (crater)
4. List of the 72 names on the Eiffel Tower
5. Sonia Delaunay
6. Corps des mines
7. Tropical year
8. N-body problem
9. Michel Eugène Chevreul
10. Poincaré and the Three-Body Problem
11. Orphism (art)
12. Metre
13. List of astronomers
14. List of French astronomers
15. List of theoretical physicists
16. History of the metre
17. Paris Observatory
18. George William Hill
19. Lunar theory
20. List of people with craters of the Moon named after them