Famous French Astronomers

Though French scholar Pierre-Simon Laplace is primarily known for his work on the solar system, his research extended to areas such as mathematics and physics, apart from astronomy. Widely known as the Newton of France, he escaped being executed during the French Revolution, owing to his lack of political views.

Joseph Louis Lagrange was an Italian mathematician and astronomer who made significant contributions to the fields of number theory, analysis, and both classical and celestial mechanics. He served as the director of mathematics at the Prussian Academy of Sciences in Berlin for over 20 years. He later moved to France and became a member of the French Academy of Sciences. 

French astronomer Charles Messier is remembered for his pioneering tabulation of nebulae, making it easier to differentiate between nebulae and comets. King Louis XV name him The Comet Ferret. He was drawn to astronomy when he witnessed a solar eclipse and the great six-tailed comet in childhood.

French physicist and mathematician François Arago discovered rotatory magnetism, named Arago's rotations. He is also remembered for his research on the wave theory of light and for the reforms he introduced as the French minister of war and the navy. The Eiffel Tower has his name inscribed on it.

Of French astronomer Guillaume Le Gentil’s discoveries, the most notable remain the Messier objects M32, M36, and M38. He waited for 8 years in India to observe the transit of Venus, but bad weather prevented his mission. He was mistakenly declared dead in France, but went back to reclaim his life.

French astronomer Urbain Le Verrier revolutionized celestial mechanics by ascertaining the existence of Neptune by mathematical means. Apart from winning the Royal Society of London’s Copley Medal, he had also led the Observatory of Paris as its director. His name remains one of the 72 engraved on the Eiffel Tower.

Johann Heinrich Lambert was a Swiss polymath whose contributions to the fields of physics, mathematics, map projections, astronomy, and philosophy are considered important by many scholars. He is credited with introducing hyperbolic functions into trigonometry. He is also credited with inventing a hygrometer, which is used to measure the quantity of water vapor in soil and air.

French Catholic priest and astronomer Pierre Gassendi is remembered for his efforts to reconcile atomism with Christian ideals and for his anti-Aristotelianism. His studies included research on Epicurean philosophy. Apart from observing the transit of Mercury, he also studied the speed of sound and horizontal momentum.

French astronomer Camille Flammarion began his career as a human computer at the Paris Observatory at 16. He believed intelligent beings from Mars had tried to communicate with people on Earth in the past. He also published L'Astronomie and penned sci-fi novels such as Omega: The Last Days of the World.

Apart from discovering helium, astronomer Pierre Janssen also found out a way of observing solar prominences with an eclipse. Permanently lamed due to a childhood accident, Janssen had begun his career as a bank clerk. He later taught physics, too. His photographic revolver paved the path for the motion-picture

A major figure of the French Revolution, Jean Sylvain Bailly is remembered for leading the Tennis Court Oath. He also made a name for himself as an astronomer and studied the Halley’s Comet and the satellites of Jupiter extensively. As a mayor of Paris, he later defended Marie-Antoinette and was guillotined.

Physicist Hippolyte Fizeau is best remembered for conducting the Fizeau experiment, named after him, which measured the speed of light. His other achievements include his contribution to the discovery of the Doppler effect and his description of the capacitor to improve the efficiency of the induction coil.

 Levi ben Gershon was a medieval French Jewish mathematician, philosopher, astronomer, and Talmudic scholar, famed for his rigid Aristotelianism. A prolific author, he has left several works on mathematical operations, trigonometry, geometry and philosophy, including The Book of the Wars of the Lord. While his bold expression and unconventional thoughts invited criticism, they continued to exert influences till nineteenth century.

Nicolas Louis de Lacaille was a French astronomer and geodesist. He is credited to have named 14 out of the 88 constellations. He studied rhetoric, theology, and philosophy and became an abbot. He later found employment as a professor of mathematics in the Mazarin college and was made a foreign member of the Royal Swedish Academy of Sciences. 

Born to a math teacher, French mathematician and physicist Alexis Clairaut had mastered calculus at 10. He is best remembered for devising the Clairaut’s equation and for validating the scientific claims of Sir Isaac Newton. He was part of an expedition to Lapland to ascertain a degree of the meridian arc.

Jean-Baptiste Biot was a French physicist, mathematician, and astronomer. He was a co-discoverer of what became known as the Biot-Savart law of magnetostatics. He is also credited with establishing the reality of meteorites. He made major contributions to the fields of optics and magnetism as well. Cape Biot in eastern Greenland is named in his honor. 

Known for his celestial observations and experiments carried out in Cayenne, Jean Richer was a French astronomer, whose works brought about a revolution in the field of astronomy, helping to determine the distances between Earth and Mars, and between Earth and Sun. In addition, they also established that the Earth is actually an oblate spheroid, not sphere, as was believed.

Sixteenth-century French mathematician Oronce Finé was also a skilled cartographer. Some of his best works remain his heart-shaped map of the world, his ivory sundial, and his woodcut map of France. He also earned a degree in medicine and was imprisoned for opposing the French king’s concordat to universities.

Jean Picard was a 17th-century French astronomer. He is known for being the first person to measure the size of the Earth to a reasonable degree of accuracy. He was also the first to attach a telescope with crosswires to a quadrant. He is credited with developing the standard method for measuring the right ascension of a celestial object. 

French explorer and mathematician Joseph Nicollet had begun his career as a math teacher at age 19. Faced with financial issues, he later moved to the U.S., where he was financially helped by a wealthy family. His exploration of the Mississippi and Missouri rivers helped him chart maps of the region.

Born to a ceiling designer, Pierre Méchain had to quit studies due to poverty. However, his talent in math earned him work as a hydrographer. A surveyor and astronomer, who spent most of his time studying deep-sky objects, he also gained fame for measuring the meridian arc from Dunkirk to Barcelona.

Jérôme Lalande was a French astronomer, freemason, and writer. His parents wanted him to study law, but he became a disciple of astronomer Joseph-Nicholas Delisle instead. He went on to have a brilliant career as an astronomer and was awarded the Lalande Prize by the French Academy of Sciences. His daughter Marie-Jeanne de Lalande also became an astronomer. 

Alexis Bouvard was a French astronomer, particularly noted for predicting the existence of an eighth planet in the solar system. Also known for discovering eight comets, he wrote Tables astronomiques of Jupiter, Saturn and Uranus; but when his tables for Uranus failed, he correctly hypothesized that an unknown planet, later discovered as Neptune, is causing irregularity in its movement.

Born to astronomer Giovanni Domenico Cassini, the director of the Paris Conservatory, Jacques Cassini, too, followed in his father’s footsteps. He opposed Sir Isaac Newton’s theory of gravity and released the preliminary tables of the satellites of Saturn. He also helped measure the longitude line between Dunkerque and Perpignan.

It is believed Jean-Baptiste-Joseph Delambre had acquired his habit of reading from his fear of losing his eyesight. He later became a professor of astronomy and served Paris Observatory as its director. He also penned significant works such as Histoire de l'astronomie. His name remains engraved on the Eiffel Tower.

French astronomer and surveyor César-François Cassini de Thury followed in his father Jacques Cassini’s footsteps to create an authentic topographical map of France. His Carte de Cassini was the first map which charted an entire country based on its topography. He had also been the director of the Paris Observatory.

The son of an affluent surgeon from Provence, Nicolas-Claude Fabri de Peiresc grew up to be a famous astronomer, known mostly for his research on longitudes. He is also remembered for discovering the Orion Nebula and owned a huge collection of coins, which he used to study history.

Twelfth-century French astronomer and scholastic philosopher William of Conches believed in the atomistic theory of nature. His works consisted of one of the earliest written works on ethics and discussions of Plato’s works. Part of the School of Chartres, he had also gained fame as a skilled grammarian.

The son of renowned French astronomer César-François Cassini de Thury, Dominique, comte de Cassini followed in his father’s footsteps to serve as the director of the Paris Observatory. He also completed the map of France that his father had begun. His monarchist ideals got him imprisoned by the revolutionary government.

French astronomer Joseph-Nicolas Delisle is best known for inventing the temperature scale known as the Delisle scale. He also studied the rings of Saturn and spent 22 years in Russia, training budding astronomers there. He also suggested a collaborative effort of scientists to study the 1761 transit of Venus.

Charles-Eugène Delaunay was a French mathematician and astronomer, known for his theory of lunar motion, explained in two volumes of La Théorie du mouvement de la lune.  A prolific writer, he wrote several other books, which contributed to the development of planetary-motion theories, functional analysis and computer algebra. In his last years, he served as the director of Paris Observatory.

After graduating from the Sorbonne and serving the army in World War II, French astronomer Gérard de Vaucouleurs focused on astronomy and later conducted extensive studies on galaxies. He often collaborated with his astronomer wife, Antoinette de Vaucouleurs, with whom he co-authored the Third Reference Catalogue of Bright Galaxies.

Johannes de Muris was not only an important philosopher and music theorist but also a respected mathematician and astronomer. His treatises titled Ars nove musice played a prominent role in the development of a 14th-century musical style called Ars nova which flourished in France in the late Middle Ages.

Bernard Lyot was a French astronomer best remembered for his invention of the Coronagraph, a device to observe the corona at any given time. He made immense contributions to the Meudon Observatory where he served as Chief Astronomer late in his career. He was honored with the prestigious Catherine Wolfe Bruce Gold Medal in 1947.

Audouin Dollfus was a French aeronaut and astronomer. He worked at the Meudon Observatory where he oversaw the operations of the Laboratory of Solar System Physics. Dollfus was the first person to use a stratospheric balloon to carry out astronomical observations. He is credited with discovering Janus, Saturn’s 10th known satellite.

Henri-Alexandre Deslandres was a French astronomer who served as the director of the Meudon Observatory. From 1907 to 1909, he also served as the president of the popular French astronomical society, the Société Astronomique de France. In 1921, he was honored with the Catherine Wolfe Bruce Gold Medal.

Félix Tisserand was a French astronomer who served as the director of the Paris Observatory from 1892 until his death in 1896. From 1893 to 1895, he served as the president of the French astronomical society, the Société Astronomique de France (SAF). One of the Moon's craters Tisserand is named in his honor.

André-Louis Danjon was a French astronomer who made immense contribution to the field of astronomy by designing the impersonal astrolabe which is currently known as the Danjon astrolabe. His contribution led to an improvement in the precision of optical astrometry. He also served as the director of the Observatory of Strasbourg and the Paris Observatory between 1930 and 1963.

Jacob ben Machir ibn Tibbon was a French Jewish physician, astronomer, and translator. A highly respected physician, Jacob also made significant contributions to astronomy in the Middle Ages. He is also credited with translating the Arabic versions of Ptolemy’s Almagest and Euclid’s Elements into Hebrew.

Jean-Baptiste-Gaspard Bochart de Saron was a French natural scientist and lawyer. He is best remembered for his contributions to astronomy. He studied the orbits of comets and worked alongside fellow astronomers like J.D. Cassini and Charles Messier. He also helped Charles Messier observe the orbit of the then-unidentified planet Uranus.

Édouard Gaston Deville was a surveyor. He is credited with perfecting a working method of photogrammetry. His invention proved useful to many Canadian surveyors who used his photo-topography to map more than 80,000 square kilometers. His invention was later used to create aerial photographs for surveying regions with high elevations as well as flat and remote parts of a nation.

Claude-Louis Mathieu was a French astronomer and mathematician. He worked at the Paris Observatory and also taught astronomy at the Collège de France. He was honored with the prestigious Lalande Prize in 1808 and 1815.