Daniel Chalonge (January 21, 1895 – November 28, 1977) 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 astrophysicist. He was born in

Grenoble Grenoble ( ; ; or ; or ) is the Prefectures in France, prefecture and List of communes in France with over 20,000 inhabitants, largest city of the Isère Departments of France, department in the Auvergne-Rhône-Alpes Regions of France, region ...

and studied in Paris under Charles Fabry. Chalonge worked as an astronomer at the

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

, the Observatoire d'Haute Provence and the Swiss Jungfraujoch Scientific Station. One of the founders of the

Institut d'astrophysique de Paris The Institut d'Astrophysique de Paris (translated: Paris Institute of Astrophysics) is a research institute in Paris, France. The Institute is part of the Sorbonne University and is associated with the CNRS Centre national de la recherche scientif ...

, his studies included the stellar

spectrum A spectrum (: spectra or spectrums) is a set of related ideas, objects, or properties whose features overlap such that they blend to form a continuum. The word ''spectrum'' was first used scientifically in optics to describe the rainbow of co ...

hydrogen Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...

, stellar

photometry Photometry can refer to: * Photometry (optics), the science of measurement of visible light in terms of its perceived brightness to human vision * Photometry (astronomy), the measurement of the flux or intensity of an astronomical object's electr ...

and classification, and measurement of the

ozone layer The ozone layer or ozone shield is a region of Earth's stratosphere that absorption (electromagnetic radiation), absorbs most of the Sun's ultraviolet radiation. It contains a high concentration of ozone (O3) in relation to other parts of the a ...

. During the Nazi occupation of France, Chalogne assumed the position of director of the Institut d'astrophysique de Paris after the previous director, Henri Mineur, was arrested by the

Gestapo The (, ), Syllabic abbreviation, abbreviated Gestapo (), was the official secret police of Nazi Germany and in German-occupied Europe. The force was created by Hermann Göring in 1933 by combining the various political police agencies of F ...

. Chalonge developed a microphotometer, which was subsequently named after him. Between 1936 and 1982 he authored (or co-authored) over 90 scientific papers. Chalonge died 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 ...

, survived by his wife and two daughters, Karen and Sonia.

Awards and honors

* Janssen Medal from 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 ...

(1949) * The crater Chalonge on 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 ...

is named after him. * Chalonge mountain in the

Alps The Alps () are some of the highest and most extensive mountain ranges in Europe, stretching approximately across eight Alpine countries (from west to east): Monaco, France, Switzerland, Italy, Liechtenstein, Germany, Austria and Slovenia. ...

is named after him. * The ''International School of Astrophysics Daniel Chalonge'' is named after him. * The ''Daniel Chalonge Museum'' in

Erice Erice (; ) is a (municipality) contiguous with the provincial capital Trapani, in western Sicily. Its historic core occupies the site of the ancient city of Eryx, one of the most significant archaeological and religious centres in pre-Roman w ...

Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...

is named after him.

References

External links

International School of Astrophysics Daniel Chalonge
1895 births 1975 deaths 20th-century French astronomers {{france-astronomer-stub