Urbain Jean Joseph Le Verrier
FRS (FOR) H
FRSE (; 11 March 1811 – 23 September 1877) was a French astronomer and mathematician who specialized in
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 ...
and is best known for predicting the existence and position of
Neptune using only
mathematics. The calculations were made to explain discrepancies with
Uranus
Uranus is the seventh planet from the Sun. Its name is a reference to the Greek god of the sky, Uranus ( Caelus), who, according to Greek mythology, was the great-grandfather of Ares (Mars), grandfather of Zeus (Jupiter) and father of ...
's
orbit
In celestial mechanics, an orbit 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 object or position in space such as ...
and the
laws of
Kepler and
Newton. Le Verrier sent the coordinates to
Johann Gottfried Galle in Berlin, asking him to verify. Galle found Neptune in the same night he received Le Verrier's letter, within 1° of the predicted position. The
discovery of Neptune is widely regarded as a dramatic validation 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 ...
, and is one of the most remarkable moments of 19th-century science.
Biography
Early years
Le Verrier was born at
Saint-Lô, Manche, France, in a modest bourgeois family, his parents being, Louis-Baptiste Le Verrier and Marie-Jeanne-Josephine-Pauline de Baudre.
He studied at
École Polytechnique
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, Savoi ...
. He briefly studied chemistry under
Gay-Lussac, writing papers on the combinations of phosphorus and hydrogen, and phosphorus and oxygen.
He then switched to astronomy, particularly celestial mechanics, and accepted a job at the
Paris Observatory. He spent most of his professional life there, and eventually became that institution's Director, from 1854 to 1870 and again from 1873 to 1877.
In 1846, Le Verrier became a member of the
French Academy of Sciences, and in 1855, he was elected a foreign member of the
Royal Swedish Academy of Sciences. Le Verrier's name is one of the
72 names inscribed on the Eiffel Tower.
Career
Early work
Le Verrier's first work in astronomy was presented to the ''Académie des Sciences'' in September 1839, entitled ''Sur les variations séculaires des orbites des planètes'' (''On the Secular Variations of the Orbits of the Planets''). This work addressed the then most-important question in astronomy: the
stability of the Solar System
The stability of the Solar System is a subject of much inquiry in astronomy. Though the planets have been stable when historically observed, and will be in the short term, their weak gravitational effects on one another can add up in unpredictable ...
, first investigated by
Laplace. He was able to derive some important limits on the motions of the system, but due to the inaccurately-known masses of the planets, his results were tentative.
From 1844 to 1847, Le Verrier published a series of works on periodic
comet
A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ...
s, in particular those of
Lexell,
Faye __NOTOC__
Faye may refer to:
Places
* Faye, Loir-et-Cher, France, a village
* Faye-d'Anjou, France, a village
* La Faye, France, a village
* Faye, Kentucky, Elliott County, Kentucky, United States
* Faye (crater), a lunar impact crater in the sout ...
and
DeVico. He was able to show some interesting interactions with the planet
Jupiter
Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth t ...
, proving that certain comets were actually the reappearance of previously-known comets flung into different orbits.
[
]
Discovery of Neptune
Le Verrier's most famous achievement is his prediction of the existence of the then unknown planet Neptune, using only mathematics and astronomical observations of the known planet Uranus. Encouraged by physicist
Arago, Director of the Paris Observatory, Le Verrier was intensely engaged for months in complex calculations to explain small but systematic discrepancies between
Uranus
Uranus is the seventh planet from the Sun. Its name is a reference to the Greek god of the sky, Uranus ( Caelus), who, according to Greek mythology, was the great-grandfather of Ares (Mars), grandfather of Zeus (Jupiter) and father of ...
's observed
orbit
In celestial mechanics, an orbit 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 object or position in space such as ...
and the one predicted from the
laws of gravity of
Newton. At the same time, but unknown to Le Verrier, similar calculations were made by
John Couch Adams in England. Le Verrier announced his final predicted position for Uranus's unseen perturbing
planet
A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...
publicly to the French Academy on 31 August 1846, two days before Adams's final solution was privately mailed to the
Royal Greenwich Observatory. Le Verrier transmitted his own prediction by 18 September in a letter to
Johann Galle of the
Berlin Observatory
The Berlin Observatory (Berliner Sternwarte) is a German astronomical institution with a series of observatories and related organizations in and around the city of Berlin in Germany, starting from the 18th century. It has its origins in 1700 w ...
. The letter arrived five days later, and the planet was found with the Berlin Fraunhofer refractor that same evening, 23 September 1846, by Galle and
Heinrich d'Arrest within 1° of the predicted location near the boundary between
Capricorn and
Aquarius.
There was, and to an extent still is, controversy over the apportionment of credit for the discovery. There is no ambiguity to the discovery claims of Le Verrier, Galle, and d'Arrest. Adams's work was begun earlier than Le Verrier's but was finished later and was unrelated to the actual discovery. Not even the briefest account of Adams's predicted orbital elements was published until more than a month after Berlin's visual confirmation. Adams made full public acknowledgement of Le Verrier's priority and credit (not forgetting to mention the role of Galle) when he gave his paper to the Royal Astronomical Society in November 1846:
Tables of the planets
Early in the 19th century, the methods of predicting the motions of the planets were somewhat scattered, having been developed over decades by many different researchers. In 1847, Le Verrier took on the task to "... embrace in a single work the entire planetary system, put everything in harmony if possible, otherwise, declare with certainty that there are as yet unknown causes of perturbations...",
a work which would occupy him for the rest of his life.
Le Verrier began by re-evaluating, to the 7th order, the technique of calculating the
planetary perturbations known as the perturbing function. This derivation, which resulted in 469 mathematical terms, was complete by 1849. He next collected observations of the positions of the planets as far back as 1750. Examining these and correcting for inconsistencies with the most recent data occupied him until 1852.
Le Verrier published, in the ''Annales de l'Observatoire de Paris'', tables of the motions of all of the known planets, releasing them as he completed them, starting in 1858.
The tables formed the
fundamental ephemeris of the ''
Connaissance des Temps
The ''Connaissance des temps'' (English: Knowledge of the Times) is an official yearly publication of astronomical ephemerides in France. Until just after the French Revolution, the title appeared as ''Connoissance des temps'', and for several ye ...
'', the astronomical almanac of the ''
Bureau des Longitudes'', until about 1912.
About that time, Le Verrier's work on the outer planets was revised and expanded by
Gaillot.
Precession of Mercury
Le Verrier began studying the motion of
Mercury as early as 1843, with a report entitled ''Détermination nouvelle de l ’orbite de Mercure et de ses perturbations'' (''A New Determination of the Orbit of Mercury and its Perturbations'').
In 1859, Le Verrier was the first to report that the slow
precession
Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In oth ...
of
Mercury’s orbit around the
Sun
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
could not be completely explained by
Newtonian mechanics and perturbations by the known planets. He suggested, among possible explanations, that another planet (or perhaps, instead, a series of smaller 'corpuscules') might exist in an orbit even closer to the Sun than that of Mercury, to account for this perturbation. (Other explanations considered included a slight oblateness of the Sun.) The success of the search for
Neptune based on its perturbations of the orbit of
Uranus
Uranus is the seventh planet from the Sun. Its name is a reference to the Greek god of the sky, Uranus ( Caelus), who, according to Greek mythology, was the great-grandfather of Ares (Mars), grandfather of Zeus (Jupiter) and father of ...
led astronomers to place some faith in this possible explanation, and the hypothetical planet was even named
Vulcan
Vulcan may refer to:
Mythology
* Vulcan (mythology), the god of fire, volcanoes, metalworking, and the forge in Roman mythology
Arts, entertainment and media Film and television
* Vulcan (''Star Trek''), name of a fictional race and their home p ...
. However, no such planet was ever found, and the anomalous precession was eventually explained by
general relativity theory.
Later life
Le Verrier's methods of management were disliked by the staff of the ''Observatoire'', and the disputes became so great that he was driven out in 1870. He was succeeded by
Delaunay, but was reinstated in 1873 after Delaunay accidentally drowned. Le Verrier held the position until his death in 1877.
[
]
Le Verrier married Lucille Clotilde Choquet in 1837 and had 3 children. He died in Paris, France and was buried in the
Montparnasse Cemetery. A large stone celestial globe sits over his grave. He will be remembered by the phrase attributed to
Arago: "the man who discovered a planet with the point of his pen."
In 1847, he was elected to the
American Philosophical Society
The American Philosophical Society (APS), founded in 1743 in Philadelphia, is a scholarly organization that promotes knowledge in the sciences and humanities through research, professional meetings, publications, library resources, and communit ...
.
Honours
*
Gold Medal of the Royal Astronomical Society
The Gold Medal of the Royal Astronomical Society is the highest award given by the Royal Astronomical Society (RAS). The RAS Council have "complete freedom as to the grounds on which it is awarded" and it can be awarded for any reason. Past awar ...
– 1868 and 1876
* Namesake of
craters on the
Moon
The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
and
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...
, a
ring of Neptune, and the
asteroid 1997 Leverrier
* One of
the 72 names engraved on the Eiffel Tower
See also
*
Discovery of Neptune
*
List of works by Henri Chapu Statue of Le Verrier
References
Further reading
* .
*
* .
* .
* .
*
* .
* .
External links
Le Verrier on the French 50 Franc banknote*
Obituary– ''Nature'', 1877, vol. 16, p. 453
Interesting interview with M. LeVerrier, director of the Paris Observatory- ''New York Herald'', 14 April 1877, p. 7
* Archived a
Ghostarchiveand th
Wayback Machine
Virtual exhibition on Paris Observatory digital libraryLe Verrier's works digitalizedon
Paris Observatory digital library
{{DEFAULTSORT:Le Verrier, Urbain
1811 births
1877 deaths
People from Saint-Lô
École Polytechnique alumni
Burials at Montparnasse Cemetery
19th-century French astronomers
French Roman Catholics
19th-century French mathematicians
Lycée Louis-le-Grand alumni
Members of the French Academy of Sciences
Members of the Royal Swedish Academy of Sciences
Foreign Members of the Royal Society
Neptune
Recipients of the Gold Medal of the Royal Astronomical Society
Recipients of the Copley Medal
Discoverers of astronomical objects