Oort, Jan Hendrik

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Oort, Jan Hendrik

(ōrt), 1900–1992, Dutch astronomer. He confirmed (1927) Bertil Lindblad's theory of the Milky Way galaxy's rotation. In the 1950s he and his colleagues used radio astronomical means to map the spiral-arm structure of the galaxy. Oort proposed (1950) that cometscomet
[Gr.,=longhaired], a small celestial body consisting mostly of dust and gases that moves in an elongated elliptical or nearly parabolic orbit around the sun or another star. Comets visible from the earth can be seen for periods ranging from a few days to several months.
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 originate in a cloud of material (the Oort cloud) orbiting the sun at great distance and that they are occasionally deflected into the inner solar system by gravitational perturbation from the passing of nearby stars.

Oort, Jan Hendrik

 

Born Apr. 28, 1900, in Franeker. Dutch astronomer. Professor at the University of Leiden (1935).

In 1924, Oort began working at the Leiden Observatory, and from 1945 to 1970 he was its director. He is primarily involved in the study of stellar motion. In 1927 he proposed formulas for the detection of the differential rotation of the Milky Way Galaxy by observing the radial velocities and proper motions of the stars; applying his formulas, he demonstrated the rotation of the galaxy. In 1938 he proposed a method for determining the spatial density distribution of the stars. He also worked on problems involving the structure of the interstellar medium and the Milky Way Galaxy using cosmic radio-emission data. From 1935 to 1948 he was secretary-general and from 1958 to 1961 president of the International Astronomical Union. He is a foreign member of the Academy of Sciences of the USSR (1966).

WORKS

“Investigations Concerning the Rotational Motion of the Galactic System.” Bulletin of the Astronomical Institutes of the Netherlands, 1927, vol. 4.
“Dynamics of the Galactic System in the Vicinity of the Sun.” Ibid., 1928, vol. 4.
“Absorption and Density Distribution in the Galactic System.” Ibid., 1938, vol. 8.
References in periodicals archive ?
Now, with the Russian Web/PC version of Astro Lords: Oort Cloud released with Tartezal Holdings at the end of May, the European and US releases of this promising multi-platform MMORTS are in the pipeline, too.
The Oort Cloud is an immense spherical cloud surrounding the solar system between 1,000 and 100,000 AU (30 trillion km) from the Sun.
Oort estimated that perhaps 20 percent of the original cloud had thus been hurled inward (or outward into interstellar space), but an ample number remained to supply more comets for the indefinite future.
Oort proposed that a vast cloud ofunseen comets surrounds the Sun at immense distances and that all the comes we see are the deserters and refugees from that distance assemblage.
The new estimate places the star firmly within the inner Oort Cloud 1.
Scientists who studied the orbit of K2 have concluded that it originated from a region in space known as the Oort Cloud.
When the stars buzzed the solar system, they probably slipped inside the Oort cloud, a shell of trillions of comets hypothesized to envelop the solar system, the researchers report in the Feb.
Siding Spring came from the Oort Cloud, a spherical region of space surrounding our sun and occupying space at a distance between 5,000 and 100,000 astronomical units.
The event was hosted by local MC Oort Kuiper and featured performances from the Street Dance judges: Leighton Wall, Ebony Roberts and Leanne Murray.
This is likely one of thousands of distant objects that are thought to form the so-called inner Oort cloud.
With the discovery of 2012 VP113 it is now clear Sedna is not unique and is likely the second known member of the hypothesized inner Oort cloud, the likely origin of some comets.