Ernest Benjamin Esclangon (17 March 1876 – 28 January 1954) was a French

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either ...

and

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change. History On ...

. Born in

Mison Mison () is a commune in the Alpes-de-Haute-Provence department in southeastern France. At the top of the hill in the village are the remains of a 13th-century castle built by the Mérvouillon family. The building is organised around a central ...

, Alpes-de-Haute-Provence, in 1895 he started to study mathematics at the

École Normale Supérieure École may refer to: * an elementary school in the French educational stages normally followed by secondary education establishments (collège and lycée) * École (river), a tributary of the Seine flowing in région Île-de-France * École, S ...

, graduating in 1898. Looking for some means of financial support while he completed his doctorate on quasi-periodic functions, he took a post at the Bordeaux Observatory, teaching some mathematics at the

university A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United States ...

. During

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

, he worked on ballistics and developed a novel method for precisely locating enemy artillery. When a gun is fired, it initiates a spherical

shock wave In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a me ...

but the projectile also generates a conical wave. By using the sound of distant guns to compare the two waves, Escaglon was able to make accurate predictions of gun locations. After the

armistice An armistice is a formal agreement of warring parties to stop fighting. It is not necessarily the end of a war, as it may constitute only a cessation of hostilities while an attempt is made to negotiate a lasting peace. It is derived from the ...

in 1919, Esclangon became director of the Strasbourg Observatory and professor of astronomy at the

the following year. In 1929, he was appointed director of the Paris Observatory and of the

International Time Bureau The International Time Bureau (french: Bureau International de l'Heure, abbreviated BIH), seated at the Paris Observatory, was the international bureau responsible for combining different measurements of Universal Time. The bureau also played an i ...

, and elected to the Bureau des Longitudes in 1932. He is perhaps best remembered for initiating in 1933 the first ''

speaking clock A speaking clock or talking clock is a live or recorded human voice service, usually accessed by telephone, that gives the correct time. The first telephone speaking clock service was introduced in France, in association with the Paris Observ ...

'' service, reportedly to relieve the observatory staff from the numerous telephone calls requesting the exact time. He was elected to the

Académie des Sciences The French Academy of Sciences (French: ''Académie des sciences'') is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French scientific research. It was at th ...

in 1939. Esclangon was the President of the Société astronomique de France (SAF), the French astronomical society, from 1933–1935.de la Société astronomique de France'', November 1937, plates X–IX
/ref> In 1935, he received the Prix Jules Janssen, the society's highest award. Serving as director of the Paris Observatory throughout

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...

and the

German occupation of Paris Paris started mobilizing for war in September 1939, when Nazi Germany and the Soviet Union attacked Poland, but the war seemed far away until May 10, 1940, when the Germans attacked France and quickly defeated the French army. The French governme ...

, he retired in 1944. He died in Eyrenville, France. The

binary asteroid A binary asteroid is a system of two asteroids orbiting their common barycenter. The binary nature of 243 Ida was discovered when the Galileo spacecraft flew by the asteroid in 1993. Since then numerous binary asteroids and several triple a ...

1509 Esclangona 1509 Esclangona, provisional designation , is a rare-type Hungaria asteroid and binary system from the inner regions of the asteroid belt, approximately 8 kilometers in diameter. It is named after French astronomer Ernest Esclangon. Discoverie ...

is named after him. The lunar crater Esclangon is named after him.

References

External links

* {{DEFAULTSORT:Esclangon, Ernest 20th-century French astronomers 1876 births 1954 deaths Members of the French Academy of Sciences École Normale Supérieure alumni Academic staff of the University of Strasbourg People from Alpes-de-Haute-Provence 20th-century French mathematicians Presidents of the International Astronomical Union