Marcel Minnaert
Encyclopedia
Belgium
Belgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...
astronomer
Astronomer
An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...
.
He obtained a PhD
PHD
PHD may refer to:*Ph.D., a doctorate of philosophy*Ph.D. , a 1980s British group*PHD finger, a protein sequence*PHD Mountain Software, an outdoor clothing and equipment company*PhD Docbook renderer, an XML renderer...
in biology
Biology
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...
at Ghent University
Ghent University
Ghent University is a Dutch-speaking public university located in Ghent, Belgium. It is one of the larger Flemish universities, consisting of 32,000 students and 7,100 staff members. The current rector is Paul Van Cauwenberge.It was established in 1817 by King William I of the Netherlands...
in 1914.
He was a supporter of the Flemish movement
Flemish movement
The Flemish Movement is a popular term used to describe the political movement for emancipation and greater autonomy of the Belgian region of Flanders, for protection of the Dutch language, and for the over-all protection of Flemish culture and history....
during World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...
and endorsed the replacement of French
French language
French is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the regions of Quebec and Acadia in Canada, and by various communities elsewhere. Second-language speakers of French are distributed throughout many parts...
by Dutch
Dutch language
Dutch is a West Germanic language and the native language of the majority of the population of the Netherlands, Belgium, and Suriname, the three member states of the Dutch Language Union. Most speakers live in the European Union, where it is a first language for about 23 million and a second...
during the German occupation of Belgium
Western Front (World War I)
Following the outbreak of World War I in 1914, the German Army opened the Western Front by first invading Luxembourg and Belgium, then gaining military control of important industrial regions in France. The tide of the advance was dramatically turned with the Battle of the Marne...
. Because of this, he was forced to flee Belgium after the end of the war.
In 1918, he found a position at Utrecht University
Utrecht University
Utrecht University is a university in Utrecht, Netherlands. It is one of the oldest universities in the Netherlands and one of the largest in Europe. Established March 26, 1636, it had an enrollment of 29,082 students in 2008, and employed 8,614 faculty and staff, 570 of which are full professors....
in the Netherlands
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...
,
initially to do photometric
Photometry (optics)
Photometry is the science of the measurement of light, in terms of its perceived brightness to the human eye. It is distinct from radiometry, which is the science of measurement of radiant energy in terms of absolute power; rather, in photometry, the radiant power at each wavelength is weighted by...
research. In Utrecht
Utrecht (city)
Utrecht city and municipality is the capital and most populous city of the Dutch province of Utrecht. It is located in the eastern corner of the Randstad conurbation, and is the fourth largest city of the Netherlands with a population of 312,634 on 1 Jan 2011.Utrecht's ancient city centre features...
, he became interested in astronomy
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...
, and he became a pioneer of solar
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
research. He specialized in spectroscopy
Spectroscopy
Spectroscopy is the study of the interaction between matter and radiated energy. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, e.g., by a prism. Later the concept was expanded greatly to comprise any interaction with radiative...
and the study of stellar atmosphere
Stellar atmosphere
The stellar atmosphere is the outer region of the volume of a star, lying above the stellar core, radiation zone and convection zone. It is divided into several regions of distinct character:...
s.
Minnaert was also interested in bubbles
Liquid bubble
A bubble is a globule of one substance in another, usually gas in a liquid.Due to the Marangoni effect, bubbles may remain intact when they reach the surface of the immersive substance.-Common examples:...
and musical nature of the sounds made by running water. In 1933 he published a solution for the acoustic
Acoustics
Acoustics is the interdisciplinary science that deals with the study of all mechanical waves in gases, liquids, and solids including vibration, sound, ultrasound and infrasound. A scientist who works in the field of acoustics is an acoustician while someone working in the field of acoustics...
resonance frequency of a single bubble in water, the so-called Minnaert resonance
Minnaert resonance
The Minnaert resonance is the acoustic resonance frequency of a single bubble in an infinite domain of water...
.
In 1937, he was appointed director of the stellar observatory Sonnenborgh
Sonnenborgh Observatory
Sonnenborgh - museum & observatory in Utrecht is a public astronomical observatory and museum open to the public. It is located in Utrecht, Netherlands. The university observatory was founded in 1853 and from 1854 until 1897 it was the first home of the Royal Dutch Meteorological...
in Utrecht and full professor in astronomy at the university. In 1940, he published his famous Utrecht Atlas of the solar spectrum. In 1941, he invented the Minnaert function, which is used in optical measurements of celestial bodies.
During the German occupation of the Netherlands in World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
, he was imprisoned by the
Germans because of his left-wing, anti-fascist sympathies. During his incarceration, he taught physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
and astronomy to his fellow prisoners. After the War, he was one of the founders of the Mathematisch Centrum in Amsterdam.
One of his interests was the effects of the atmosphere on light and images. His classic book on this subject was released in English translation as:
- The Nature of Light and Color in the Open Air, Dover, 1954, ISBN 0-486-20196-1
and in a new translation with color photographs as:
- Light and Color in the Outdoors, Springer, 1993, ISBN 0-387-97935-2, ISBN 3-540-97935-2, ISBN 0-387-94413-3 (originally published in Dutch in 1937 as De natuurkunde van 't vrije veld. Licht en kleur in het landschap.)
Honors
Awards- Gold Medal of the Royal Astronomical SocietyGold Medal of the Royal Astronomical Society-History:In the early years, more than one medal was often awarded in a year, but by 1833 only one medal was being awarded per year. This caused a problem when Neptune was discovered in 1846, because many felt an award should jointly be made to John Couch Adams and Urbain Le Verrier...
(1947) - Bruce MedalBruce MedalThe 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 first awarded in 1898...
(1951)
Named after him
- AsteroidAsteroidAsteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...
1670 Minnaert1670 Minnaert1670 Minnaert is a main-belt asteroid discovered on September 9, 1934 by H. van Gent at Johannesburg .- External links :*... - Minnaert (crater)Minnaert (crater)Minnaert is a large lunar crater that is located on the far side of the Moon, deep in the southern hemisphere. It is partly overlain along the southeastern side by the larger and younger crater Antoniadi. To the west-northwest lies Lyman....
on the MoonMoonThe Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more... - Minnaert building of the UithofUithofDe Uithof is the campus area of the Utrecht University and the University of Professional Education Utrecht. It is located on the east of Utrecht, near the Galgenwaard Stadium of FC Utrecht. Except for the faculties of Law, Humanities, and University College, which are located in the inner city of...
campus of Utrecht UniversityUtrecht UniversityUtrecht University is a university in Utrecht, Netherlands. It is one of the oldest universities in the Netherlands and one of the largest in Europe. Established March 26, 1636, it had an enrollment of 29,082 students in 2008, and employed 8,614 faculty and staff, 570 of which are full professors....