Édouard Albert Roche (; 17 October 1820 – 27 April 1883) was a French

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 is best known for his work in the field of

celestial mechanics Celestial mechanics is the branch of astronomy that deals with the motions of objects in outer space. Historically, celestial mechanics applies principles of physics (classical mechanics) to astronomical objects, such as stars and planets, to ...

. His name was given to the concepts of the Roche sphere,

Roche limit In celestial mechanics, the Roche limit, also called Roche radius, is the distance from a celestial body within which a second celestial body, held together only by its own force of gravity, will disintegrate because the first body's tidal force ...

, and

Roche lobe In astronomy, the Roche lobe is the region around a star in a binary system within which orbiting material is gravitationally bound to that star. It is an approximately teardrop-shaped region bounded by a critical gravitational equipotential, ...

. He also was the author of works in

meteorology Meteorology is the scientific study of the Earth's atmosphere and short-term atmospheric phenomena (i.e. weather), with a focus on weather forecasting. It has applications in the military, aviation, energy production, transport, agricultur ...

Biography

He was born in

Montpellier Montpellier (; ) is a city in southern France near the Mediterranean Sea. One of the largest urban centres in the region of Occitania (administrative region), Occitania, Montpellier is the prefecture of the Departments of France, department of ...

, and studied at the

University of Montpellier The University of Montpellier () is a public university, public research university located in Montpellier, in south-east of France. Established in 1220, the University of Montpellier is one of the List of oldest universities in continuous opera ...

, receiving his D.Sc. in 1844 and later becoming a professor at the same institution, where he served in the Faculté des Sciences starting in 1849. Roche made a mathematical study of Laplace's

nebular hypothesis The nebular hypothesis is the most widely accepted model in the field of cosmogony to explain the formation and evolution of the Solar System (as well as other planetary systems). It suggests the Solar System is formed from gas and dust orbiting t ...

and presented his results in a series of papers to the Academy of Montpellier from his appointment until 1877. The most important were on

comets A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or coma surrounding the nucleus, an ...

(1860) and the nebular hypothesis itself (1873). Roche's studies examined the effects of strong gravitational fields upon swarms of tiny particles. He is perhaps most famous for his theory that the

planetary ring A ring system is a disc or torus orbiting an astronomical object that is composed of solid material such as dust, meteoroids, planetoids, moonlets, or stellar objects. Ring systems are best known as planetary rings, common components of sate ...

s of

Saturn Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about 9 times that of Earth. It has an eighth the average density of Earth, but is over 95 tim ...

were formed when a large icy

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 ...

came too close to Saturn and was pulled apart by

gravitation In physics, gravity (), also known as gravitation or a gravitational interaction, is a fundamental interaction, a mutual attraction between all massive particles. On Earth, gravity takes a slightly different meaning: the observed force b ...

al forces. He described a method of calculating the distance at which an object held together only by gravity would break up due to

tidal force The tidal force or tide-generating force is the difference in gravitational attraction between different points in a gravitational field, causing bodies to be pulled unevenly and as a result are being stretched towards the attraction. It is the ...

s; this distance became known as the Roche limit. His other best known works also involved orbital mechanics. The Roche sphere describes the limits at which an object which is in orbit around two other objects will be captured by one or the other, and the Roche lobe approximates the gravitational sphere of influence of one

astronomical body An astronomical object, celestial object, stellar object or heavenly body is a naturally occurring physical object, physical entity, association, or structure that exists within the observable universe. In astronomy, the terms ''object'' and ...

in the face of perturbations from another heavier body around which it

orbit In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an ...

s. Roche's works were not appreciated during his lifetime. In 1883 he was proposed for full membership to 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 ...

. However, he only received a single vote out of 56. He died of pneumonia two days later, unaware that his membership had been declined.

Works

Roche's works are in French, his vernacular language.

Lists of works

List of works
on the site of the

Académie des 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 ...

(31 items) (Includes—unnumbered—works commenting that of Roche. Also includes works in meteorology) * , in ''Mémoires de la Société des sciences, de l'agriculture et des arts de Lille'', 1885 (34 items)

References

* Z. Kopal, ''The Roche problem'',

Kluwer Academic Publishers Springer Science+Business Media, commonly known as Springer, is a German multinational publishing company of books, e-books and peer-reviewed journals in science, humanities, technical and medical (STM) publishing. Originally founded in 1842 in ...

, Dordrecht, 1989 . {{DEFAULTSORT:Roche, Edouard 1820 births 1883 deaths Scientists from Montpellier 19th-century French astronomers 19th-century French mathematicians Tidal forces

Biography

Works

Lists of works

See also

References