Bernard Ferdinand Lyot (2 7 February 1897 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 ...

– 2 April 1952 in

Cairo Cairo ( ; , ) is the Capital city, capital and largest city of Egypt and the Cairo Governorate, being home to more than 10 million people. It is also part of the List of urban agglomerations in Africa, largest urban agglomeration in Africa, L ...

) 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 ...

Biography

An avid reader of the works of

Camille Flammarion Nicolas Camille Flammarion FRAS (; 26 February 1842 – 3 June 1925) was a French astronomer and author. He was a prolific author of more than fifty titles, including popular science works about astronomy, several notable early science fiction ...

, he became a member of the

Société Astronomique de France The Société astronomique de France (SAF; ), the France, French astronomical society, is a non-profit association in the public interest organized under French law (Association loi de 1901). Founded by astronomer Camille Flammarion in 1887, its ...

in 1915 and made his first observations using the society's telescope on rue Serpente in Paris. He soon acquired a telescope and soon upgraded to a . From graduation in 1918 until 1929, he worked as a demonstrator at the

École Polytechnique (, ; also known as Polytechnique or l'X ) is a ''grande école'' located in Palaiseau, France. It specializes in science and engineering and is a founding member of the Polytechnic Institute of Paris. The school was founded in 1794 by mat ...

and studied

engineering Engineering is the practice of using natural science, mathematics, and the engineering design process to Problem solving#Engineering, solve problems within technology, increase efficiency and productivity, and improve Systems engineering, s ...

physics Physics is the scientific study of matter, its Elementary particle, fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge whi ...

, and

chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a physical science within the natural sciences that studies the chemical elements that make up matter and chemical compound, compounds made of atoms, molecules a ...

at the

University of Paris The University of Paris (), known Metonymy, metonymically as the Sorbonne (), was the leading university in Paris, France, from 1150 to 1970, except for 1793–1806 during the French Revolution. Emerging around 1150 as a corporation associated wit ...

. From 1920 until his death he worked for the

Meudon Observatory The Paris Observatory (, ), a research institution of the Paris Sciences et Lettres University, is the foremost astronomy, astronomical observatory of France, and one of the largest astronomical centres in the world. Its historic building is on t ...

, where in 1930 he earned the title of ''Joint Astronomer of the Observatory''. After gaining the title, he earned a reputation of being an expert of polarized and monochromatic light. Throughout the 1930s, he labored to perfect the

coronagraph A coronagraph is a telescopic attachment designed to block out the direct light from a star or other bright object so that nearby objects – which otherwise would be hidden in the object's bright glare – can be resolved. Most coronagr ...

, which he invented to observe the corona without having to wait for a solar eclipse. Most of this work implied painstaking long observations at the Pic du Midi Observatory. It was an exceptionally good site, free of both air pollution and

light pollution Light pollution is the presence of any unwanted, inappropriate, or excessive artificial Visible spectrum, lighting. In a descriptive sense, the term ''light pollution'' refers to the effects of any poorly implemented lighting sources, during the ...

but it came with a disadvantage: In the interwar period access to the peak implied mountaineering skills and physical fitness, especially in winter when access was only gained with a long and tiresome

ski touring Ski touring is skiing in the backcountry on unmarked or unpatrolled areas. Touring is typically done off-piste and outside of ski resorts, and may extend over a period of more than one day. It is similar to backcountry skiing but excludes the ...

trek on sealskin-fitted skis, a technique mastered by Lyot, a keen sportsman and mountaineer. Accommodation on site can only be described as spartan, before a powerline, a bigger refuge and a cablecar were built in the early 1950s. In 1938, he showed a movie of the corona in action to the

International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

. In 1939, he was elected 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 ...

. He became Chief Astronomer at the Meudon Observatory in 1943 and received the

Bruce Medal The Catherine Wolfe Bruce Gold Medal is awarded every year by the Astronomical Society of the Pacific for outstanding lifetime contributions to astronomy. It is named after Catherine Wolfe Bruce, an American patroness of astronomy, and was ...

in 1947. Lyot was the President of the

Société astronomique de France The Société astronomique de France (SAF; ), the France, French astronomical society, is a non-profit association in the public interest organized under French law (Association loi de 1901). Founded by astronomer Camille Flammarion in 1887, its ...

, the French astronomical society, from 1945-1947. He suffered a heart attack while returning from an eclipse expedition in Sudan and died on 2 April 1952, at the age of 55.

Observations and Achievements on Pic du Midi

*Lunar soil behaves like volcanic dust. *

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 ...

has sandstorms. *Improved his

. *Made

motion pictures A film, also known as a movie or motion picture, is a work of visual art that simulates experiences and otherwise communicates ideas, stories, perceptions, emotions, or atmosphere through the use of moving images that are generally, sinc ...

solar prominence In solar physics, a prominence, sometimes referred to as a filament, is a large Plasma (physics), plasma and magnetic field structure extending outward from the Sun's surface, often in a loop shape. Prominences are anchored to the Sun's surface ...

s and the corona. *Found

spectral lines A spectral line is a weaker or stronger region in an otherwise uniform and continuous spectrum. It may result from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used ...

in the corona.

Inventions

Coronagraph A coronagraph is a telescopic attachment designed to block out the direct light from a star or other bright object so that nearby objects – which otherwise would be hidden in the object's bright glare – can be resolved. Most coronagr ...

* Lyot filter * Lyot stop * Lyot depolarizer

Awards and honors

Awards * Lalande Prize from the

* Janssen Medal from the

(1930) * Prix Jules Janssen, the highest award of the

(1932) *

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 ...

(1939) * Howard N. Potts Medal (1942) *

(1947) * Henry Draper Medal of the

National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, NGO, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the ...

(1951) Named for him * Lyot (lunar crater). *

Lyot (Martian crater) Lyot is a large Peak ring (crater), peak ring crater in the Vastitas Borealis region of Mars, located at 50.8° north latitude and 330.7° west longitude within the Ismenius Lacus quadrangle. It is 236 km in diameter. Its name refers to Ber ...

. *

Minor planet According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor ...

2452 Lyot.

References

{{DEFAULTSORT:Lyot, Bernard 1897 births 1952 deaths Scientists from Paris 20th-century French astronomers 20th-century French inventors Members of the French Academy of Sciences Foreign associates of the National Academy of Sciences Recipients of the Gold Medal of the Royal Astronomical Society Howard N. Potts Medal recipients Recipients of the Lalande Prize University of Paris alumni