Delaunay
# Charles Eugene Delaunay

### Born: 9 April 1816
in Lusigny-sur-Barse, France

Died: 5 Aug 1872
in At sea (near Cherbourg, France)

Show birthplace location

**Delaunay** studied under Biot's direction at the Sorbonne, then worked in astronomy and mechanics. He taught mechanics at the École Polytechnique from 1850 and later taught at the École des Mines (where he had been a student).
He published, in 1860 and 1867, two volumes on lunar theory La Théorie du mouvement de la lune which were the result of 20 years work. This is an important case of the three body problem. Delaunay found the longitude, latitude and parallax of the Moon as infinite series. These gave results correct to 1 second of arc but were not too practical as the series converged slowly. However this work was important in the beginnings of functional analysis.

Delaunay succeeded Le Verrier as director of the Paris Observatory in 1870 but 2 years later he and three companions drowned in a boating accident. Among his works on mechanics were Cours élémentaire de mécanique (1850) and Traité de mécanique rationnelle (1856).

**References (4 books/articles)**

**References elsewhere in this archive:**

Tell me about Delaunay's work on orbits and gravitation

Charles E Delaunay was elected to the Royal Society of London in 1869. You can see a history of the Royal Society and a list of the members among the mathematicians in our archive.

Impasse Delaunay, Rue Delaunay and Square Delaunay are in the 11th Arrondissement in Paris. You can see a list of Paris streets named after mathematicians in our archive.

There is a **Crater Delaunay** on the moon. You can see a list of lunar features named after mathematicians.

JOC/EFR December 1996