Jan Oort
Encyclopedia
Jan Hendrik Oort was a Dutch
astronomer
. He was a pioneer in the field of radio astronomy
. The Oort cloud
of comet
s bears his name.
Oort was born in Franeker
, Friesland
and studied in Groningen with Jacobus Cornelius Kapteyn. His Ph.D thesis was titled The stars of high velocity. In 1927 he confirmed Bertil Lindblad
's theory that the Milky Way
galaxy rotates, by analyzing the movements of star
s. In 1935 he became professor at the observatory
of the University of Leiden, where Ejnar Hertzsprung
was the director.
In 1928 his son Coen Oort was born, who later became an important Dutch economist and public official and who in 1990 headed the Oort Commission, which was responsible for a major overturn of Dutch tax law.
Oort was fascinated by radio waves from the universe
. After the Second World War he began work in the new field of radio astronomy, using an old radar
antenna from the Germans
.
In the 1950s he raised funds for a new radio telescope
in Dwingeloo
, in the east part of the Netherlands, to research the center of the galaxy. In 1970 a bigger telescope (the Westerbork Synthesis Radio Telescope
) was built in Westerbork
, near the old one. It consisted of twelve smaller telescopes working together to perform radio interferometry
observations, a technique which had been previously suggested by Oort, but which was first tested experimentally in Cambridge
by Martin Ryle
and in Sydney
by Joseph Pawsey.
His hypothesis that the comet
s have a common origin, postulated in 1950, was later proven to be incorrect in detail, though correct in principle. That is, different types of comets have origins in different regions of the outer solar system. For more, see Oort Cloud
, Hills Cloud, and Kuiper Belt
. Another contribution Oort made was to demonstrate that the light from the Crab nebula
was polarized.
Awards
Named after him
Upon his death, Nobel Prize Subrahmanyan Chandrasekhar
remarked, "The great oak of Astronomy has been felled, and we are lost without its shadow."
http://bc.ub.leidenuniv.nl/bc/tentoonstelling/Jan_Oort/inhoud.htm
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...
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 was a pioneer in the field of radio astronomy
Radio astronomy
Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies. The initial detection of radio waves from an astronomical object was made in the 1930s, when Karl Jansky observed radiation coming from the Milky Way. Subsequent observations have identified a number of...
. The Oort cloud
Oort cloud
The Oort cloud , or the Öpik–Oort cloud , is a hypothesized spherical cloud of comets which may lie roughly 50,000 AU, or nearly a light-year, from the Sun. This places the cloud at nearly a quarter of the distance to Proxima Centauri, the nearest star to the Sun...
of comet
Comet
A comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet...
s bears his name.
Oort was born in Franeker
Franeker
Franeker is one of the eleven historical cities of Friesland and capital of the municipality of Franekeradeel. It is located about 20 km west of Leeuwarden on the Van Harinxma Canal. As of 1 January 2006, it had 12,996 inhabitants. The city is famous for the Eisinga Planetarium from around...
, Friesland
Friesland
Friesland is a province in the north of the Netherlands and part of the ancient region of Frisia.Until the end of 1996, the province bore Friesland as its official name. In 1997 this Dutch name lost its official status to the Frisian Fryslân...
and studied in Groningen with Jacobus Cornelius Kapteyn. His Ph.D thesis was titled The stars of high velocity. In 1927 he confirmed Bertil Lindblad
Bertil Lindblad
Bertil Lindblad Bertil Lindblad Bertil Lindblad (Örebro, 26 November 1895 – Saltsjöbaden (outside Stockholm, 25 June 1965) was a Swedish astronomer.After finishing his secondary education at Örebro högre allmänna läroverk, Lindblad matriculated at Uppsala University in 1914...
's theory that the Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
galaxy rotates, by analyzing the movements of star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
s. In 1935 he became professor at the observatory
Leiden Observatory
Leiden Observatory is an astronomical observatory in the city of Leiden, Netherlands. It was established by Leiden University in 1633, to house the quadrant of Snellius, and is the oldest operating University observatory in the world Leiden Observatory (Sterrewacht Leiden in Dutch) is an...
of the University of Leiden, where Ejnar Hertzsprung
Ejnar Hertzsprung
Ejnar Hertzsprung was a Danish chemist and astronomer.Hertzsprung was born in Copenhagen. In the period 1911–1913, together with Henry Norris Russell, he developed the Hertzsprung–Russell diagram....
was the director.
In 1928 his son Coen Oort was born, who later became an important Dutch economist and public official and who in 1990 headed the Oort Commission, which was responsible for a major overturn of Dutch tax law.
Oort was fascinated by radio waves from the universe
Universe
The Universe is commonly defined as the totality of everything that exists, including all matter and energy, the planets, stars, galaxies, and the contents of intergalactic space. Definitions and usage vary and similar terms include the cosmos, the world and nature...
. After the Second World War he began work in the new field of radio astronomy, using an old radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
antenna from the Germans
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
.
In the 1950s he raised funds for a new radio telescope
Radio telescope
A radio telescope is a form of directional radio antenna used in radio astronomy. The same types of antennas are also used in tracking and collecting data from satellites and space probes...
in Dwingeloo
Dwingeloo
Dwingeloo is a town halfway between Meppel and Assen in the Dutch province of Drenthe. It is a part of the municipality of Westerveld.The town is known internationally because of the radio telescope of the Dwingeloo Radio Observatory , located on the edge of the Dwingeloo Heath, 3 km south of...
, in the east part of the Netherlands, to research the center of the galaxy. In 1970 a bigger telescope (the Westerbork Synthesis Radio Telescope
Westerbork Synthesis Radio Telescope
The Westerbork Synthesis Radio Telescope is an aperture synthesis interferometer near camp Westerbork, north of the village of Westerbork, Midden-Drenthe, in the northeastern Netherlands. It consists of a linear array of 14 antennas with a diameter of 25 metres arranged on a 2.7 km East-West line...
) was built in Westerbork
Midden-Drenthe
Midden-Drenthe is a municipality in the northeastern Netherlands. The municipality was created in 1998, in a merger of the former municipalities of Beilen, Smilde, and Westerbork...
, near the old one. It consisted of twelve smaller telescopes working together to perform radio interferometry
Interferometry
Interferometry refers to a family of techniques in which electromagnetic waves are superimposed in order to extract information about the waves. An instrument used to interfere waves is called an interferometer. Interferometry is an important investigative technique in the fields of astronomy,...
observations, a technique which had been previously suggested by Oort, but which was first tested experimentally in Cambridge
University of Cambridge
The University of Cambridge is a public research university located in Cambridge, United Kingdom. It is the second-oldest university in both the United Kingdom and the English-speaking world , and the seventh-oldest globally...
by Martin Ryle
Martin Ryle
Sir Martin Ryle was an English radio astronomer who developed revolutionary radio telescope systems and used them for accurate location and imaging of weak radio sources...
and in Sydney
University of Sydney
The University of Sydney is a public university located in Sydney, New South Wales. The main campus spreads across the suburbs of Camperdown and Darlington on the southwestern outskirts of the Sydney CBD. Founded in 1850, it is the oldest university in Australia and Oceania...
by Joseph Pawsey.
His hypothesis that the comet
Comet
A comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet...
s have a common origin, postulated in 1950, was later proven to be incorrect in detail, though correct in principle. That is, different types of comets have origins in different regions of the outer solar system. For more, see Oort Cloud
Oort cloud
The Oort cloud , or the Öpik–Oort cloud , is a hypothesized spherical cloud of comets which may lie roughly 50,000 AU, or nearly a light-year, from the Sun. This places the cloud at nearly a quarter of the distance to Proxima Centauri, the nearest star to the Sun...
, Hills Cloud, and Kuiper Belt
Kuiper belt
The Kuiper belt , sometimes called the Edgeworth–Kuiper belt, is a region of the Solar System beyond the planets extending from the orbit of Neptune to approximately 50 AU from the Sun. It is similar to the asteroid belt, although it is far larger—20 times as wide and 20 to 200 times as massive...
. Another contribution Oort made was to demonstrate that the light from the Crab nebula
Crab Nebula
The Crab Nebula is a supernova remnant and pulsar wind nebula in the constellation of Taurus...
was polarized.
A few of Oort's discoveries
- In 1924, Oort discovered the galactic haloGalactic haloThe term galactic halo is used to denote an extended, roughly spherical component of a galaxy, which extends beyond the main, visible component. It can refer to any of several distinct components which share these properties:* the galactic spheroid...
, a group of stars orbiting the Milky WayMilky WayThe Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
but outside the main disk. - In 1927, he calculated that the center of the Milky WayMilky WayThe Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
was 5,900 parsecs (19,200 light yearsLight YearsLight Years is the seventh studio album by Australian recording artist Kylie Minogue. It was released on 25 September 2000 by Parlophone and Mushroom Records. The album's style was indicative of her return to "mainstream pop dance tunes"....
) from the Earth in the direction of the constellation SagittariusSagittarius (constellation)Sagittarius is a constellation of the zodiac, the one containing the galactic center. Its name is Latin for the archer, and its symbol is , a stylized arrow. Sagittarius is commonly represented as a centaur drawing a bow...
. - He showed that the Milky Way had a mass 100 billion times that of the Sun.
- In 1950 he suggested that cometCometA comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet...
s came from a common region of the Solar System (now called the Oort cloudOort cloudThe Oort cloud , or the Öpik–Oort cloud , is a hypothesized spherical cloud of comets which may lie roughly 50,000 AU, or nearly a light-year, from the Sun. This places the cloud at nearly a quarter of the distance to Proxima Centauri, the nearest star to the Sun...
). - He found that the light from the Crab NebulaCrab NebulaThe Crab Nebula is a supernova remnant and pulsar wind nebula in the constellation of Taurus...
was polarized, and produced by synchrotron emissionSynchrotron radiationThe electromagnetic radiation emitted when charged particles are accelerated radially is called synchrotron radiation. It is produced in synchrotrons using bending magnets, undulators and/or wigglers...
.
Honors
- 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...
of the Astronomical Society of the PacificAstronomical Society of the PacificThe Astronomical Society of the Pacific is a scientific and educational organization, founded in San Francisco on February 7, 1889. Its name derives from its origins on the Pacific Coast, but today it has members all over the country and the world...
in 1942 - 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...
in 1946 - Henry Norris Russell LectureshipHenry Norris Russell LectureshipThe Henry Norris Russell Lectureship is awarded each year by the American Astronomical Society in recognition of a lifetime of excellence in astronomical research.-Previous lecturers:This list of lecturers is from the American Astronomical Society's website....
of the American Astronomical SocietyAmerican Astronomical SocietyThe American Astronomical Society is an American society of professional astronomers and other interested individuals, headquartered in Washington, DC...
in 1951 - Gouden Ganzeveer in 1960
- Karl Schwarzschild MedalKarl Schwarzschild MedalThe Karl Schwarzschild Medal, named after the astrophysicist Karl Schwarzschild, is an award presented by the Astronomische Gesellschaft to eminent astronomers and astrophysicists.-Recipients:...
of the Astronomische GesellschaftAstronomische GesellschaftThe Astronomische Gesellschaft is an astronomical society established in 1863 in Heidelberg, the second oldest astronomical society after the Royal Astronomical Society....
in 1972 - Balzan PrizeBalzan PrizeThe International Balzan Prize Foundation awards four annual monetary prizes to people or organisations who have made outstanding achievements in the fields of humanities, natural sciences, culture, as well as for endeavours for peace and the brotherhood of man.-Rewards and assets:Each year the...
for AstrophysicsAstrophysicsAstrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties of celestial objects, as well as their interactions and behavior...
in 1984
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...
1691 Oort1691 Oort1691 Oort is a main-belt asteroid discovered on September 9, 1956 by Ingrid van Houten-Groeneveld and Karl Wilhelm Reinmuth at Heidelberg. It was named after the Dutch astronomer Jan Oort.- External links :... - Oort CloudOort cloudThe Oort cloud , or the Öpik–Oort cloud , is a hypothesized spherical cloud of comets which may lie roughly 50,000 AU, or nearly a light-year, from the Sun. This places the cloud at nearly a quarter of the distance to Proxima Centauri, the nearest star to the Sun...
- Oort constants of galactic structure
Upon his death, Nobel Prize Subrahmanyan Chandrasekhar
Subrahmanyan Chandrasekhar
Subrahmanyan Chandrasekhar, FRS ) was an Indian origin American astrophysicist who, with William A. Fowler, won the 1983 Nobel Prize for Physics for key discoveries that led to the currently accepted theory on the later evolutionary stages of massive stars...
remarked, "The great oak of Astronomy has been felled, and we are lost without its shadow."
Online exhibition
Jan Oort, astronomer (Leiden University Library, April–May 2000)http://bc.ub.leidenuniv.nl/bc/tentoonstelling/Jan_Oort/inhoud.htm