Jean Charles Rodolphe Radau (22 January 1835 – 21 December 1911) was a German

astronomer An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth. Astronomers observe astronomical objects, such as stars, planets, natural satellite, moons, comets and galaxy, galax ...

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, mathematical structure, structure, space, Mathematica ...

who worked in

Paris Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, largest city of France. With an estimated population of 2,048,472 residents in January 2025 in an area of more than , Paris is the List of ci ...

at the ''Revue des deux Mondes'' for most of his life. He was the co-founder of the Bulletin Astronomique. Radau was born in Angerburg, Province of Prussia (now Węgorzewo in

Poland Poland, officially the Republic of Poland, is a country in Central Europe. It extends from the Baltic Sea in the north to the Sudetes and Carpathian Mountains in the south, bordered by Lithuania and Russia to the northeast, Belarus and Ukrai ...

), and after studying in

Königsberg Königsberg (; ; ; ; ; ; , ) is the historic Germany, German and Prussian name of the city now called Kaliningrad, Russia. The city was founded in 1255 on the site of the small Old Prussians, Old Prussian settlement ''Twangste'' by the Teuton ...

and working on the Three-body problem, he moved to Paris to collaborate with other scientists. In 1871 he was awarded a Ph.D. in recognition of his work in mathematics. Radau won the Prix Damoiseau of the

French Academy of Sciences The French Academy of 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 method, scientific research. It was at the forefron ...

in 1892 working on planetary perturbations in the motion of the

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

. This work was of such a high quality that he was elected to the Academy in 1897. A crater on

Mars Mars is the fourth planet from the Sun. It is also known as the "Red Planet", because of its orange-red appearance. Mars is a desert-like rocky planet with a tenuous carbon dioxide () atmosphere. At the average surface level the atmosph ...

is named in Radau's honor. His publications include the ''Wonders of Acoustics'' ( 1867).

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Obituaries

AN 190(1912) 251

1835 births 1911 deaths People from Węgorzewo People from the Province of Prussia 19th-century German astronomers 19th-century German mathematicians 20th-century German mathematicians Members of the French Academy of Sciences Recipients of the Lalande Prize {{Germany-mathematician-stub

See also

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Obituaries