
	Where results make sense

Topic: Jan Oort

Related Topics

Oort cloud

University of Groningen

Crab Nebula

Gerard Kuiper

Johann Galle

Mary Sue fanfiction

Ursidae

Microverse

Kuiper belt

Henry Norris Russell Lectureship

Pern

Ole Romer

Netherlands

Upper Dublin Township, Pennsylvania

Giuseppe Piazzi

In the News (Sun 5 Jul 09)

Northern Trust

Marvin Harrison

Peter Chernin

Gary Locke

Match Play

Penelope Cruz

Mickey Rourke

AR Rahman

Danny Boyle

Hugh Jackman

	Jan Oort - Wikipedia, the free encyclopedia
		Oort was born in Franeker in Friesland and studied in Groningen with Jacobus Cornelius Kapteyn.
		Another contribution of Oort was that he was able to demonstrate that the light from the Crab nebula was polarized.
		Oort calculated that the centre of the Milky Way was 30,000 light years from the Earth in the direction of the constellation Sagitarius.
	en.wikipedia.org /wiki/Jan_Oort (351 words)

	Practical Info (Oort Symposium) (Site not responding. Last check: 2007-10-08)
		Jan Hendrik Oort is undoubtedly one of the greatest astronomers of the twentieth century.
		Jan Hendrik Oort was born in the Dutch (Frisian) town of Franeker on April 28, 1900.
		Oort derived the laws for the dependence of the rotation speed on the distance from the center, introducing two constants, A and B, that are generally known as the Oort constants.
	www.strw.leidenuniv.nl /~oortsymp/jhoort.html (999 words)

	Oort cloud - Wikipedia, the free encyclopedia
		The Oort cloud is a remnant of the original nebula that collapsed to form the Sun and planets five billion years ago, and is loosely bound to the solar system.
		The most widely-accepted hypothesis of its formation is that the Oort cloud's objects initially formed much closer to the Sun as part of the same process that formed the planets and asteroids, but that gravitational interaction with young gas giants such as Jupiter ejected them into extremely long elliptical or parabolic orbits.
		It is thought that other stars are likely to possess Oort clouds of their own, and that the outer edges of two nearby stars' Oort clouds may sometimes overlap, causing the occasional intrusion of a comet into the inner solar system.
	en.wikipedia.org /wiki/Oort_cloud (681 words)

	Jan Oort -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-08)
		Jan Hendrik Oort (April 28, 1900 – November 5, 1992) was an internationally famous (The West Germanic language of the Netherlands) Dutch astronomer.
		Oort was born in (Click link for more info and facts about Franeker) Franeker in (One of the northernmost provinces of the Netherlands) Friesland and studied in (Click link for more info and facts about Groningen) Groningen with (Click link for more info and facts about Jacobus Cornelius Kapteyn) Jacobus Cornelius Kapteyn.
		Oort calculated that the centre of the (The galaxy containing the solar system; consists of millions of stars that can be seen as a diffuse band of light stretching across the night sky) Milky Way was 30.000 light years from the Earth in the direction of the constellation Sagitarius.
	www.absoluteastronomy.com /encyclopedia/j/ja/jan_oort.htm (572 words)

	ORRERY: The Oort Cloud
		In 1950, Dutch astronomer Jan Hendrik Oort [1900-92] made a study of comets with the largest orbits.
		Oort discovered that not only were the orbits concentrated towards the very large, they actually peaked out, most falling in from around 50,000 AU.
		Piecing all the mathematical evidence together, Oort concluded that the solar system is surrounded by a vast sphere of icy rocks (comet nuclei) at a distance of 50,000 AU - over 1200× the distance of Pluto from the Sun - that occasionally fall in to visit us.
	www.harmsy.freeuk.com /oort.html (305 words)

	Jan Oort - Wikipedia, the free encyclopedia (Site not responding. Last check: 2007-10-08)
		Jan Hendrik Oort (April 28, 1900 – November 5, 1992) was an internationally famous Dutch astronomer.
		After the Second World War he was a pioneer in the new field of radio astronomy, using an old from the Germans.
		It consisted of twelve smaller telescopes working together as an interferometer to perform aperture synthesis 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.
	www.sevenhills.us /project/wikipedia/index.php/Jan_Oort (378 words)

	Oort, Jan Hendrik (1900-1992)
		More or less as a sideline, Oort studied comets as well and provided evidence for his theory, now widely accepted, that the Sun is surrounded by a distant cloud of ice-rock objects that has become known as the Oort Cloud.
		Oort studied stellar dynamics under Jacobus Kapteyn at Groningen and worked at the University of Leiden from 1924 to 1992.
		During World War II Oort started his compatriot Hendrik van der Hulst on the successful search for the 21-cm neutral hydrogen line and after the war led the Dutch group that used the 21-cm line to map the layout of the Galaxy, including the large-scale spiral structure, the galactic center, and gas cloud motions.
	www.daviddarling.info /encyclopedia/O/Oort.html (288 words)

	Oort Cloud
		It is named after Jan Oort, though Ernst Öpik was the first to postulate its existence.
		Studies of the orbits of long-period comets, which are believed to originate in the Oort Cloud, suggest that the Cloud extends out from a heliocentric distance of about 20,000 to 100,000 astronomical units, with a peak density of objects at 44,000 AU from the Sun.
		If it were the case that the Oort Cloud comets originated at a wide range of distances, from the orbit of Jupiter to that of Neptune, and therefore at a wide range of ambient temperatures, this would explain the differences in composition observed in long-period comets.
	www.daviddarling.info /encyclopedia/O/OortCloud.html (587 words)

	Lamont-Doherty Earth Observatory - Biography of Vetlesen Prize Winner - Jan Hendrik Oort
		Jan Hendrik Oort, without a doubt one of the greatest astronomers of the twentieth century, was born in the Dutch town of Franeker on April 28, 1900.
		Oort is probably best known for showing that the motions of stars in the solar neighborhood reveal the effects of differential rotation.
		Jan Hendrik Oort died on November 5, 1992, leaving behind an impressive legacy in nearly every field of stellar astronomy and astrophysics.
	www.ldeo.columbia.edu /vetlesen/recipients/1966/oort_bio.html (458 words)

	Oort Cloud
		The Oort cloud is an immense spherical cloud surrounding the planetary system and extending approximately 3 light years, about 30 trillion kilometers from the Sun.
		One sixth of an estimated six trillion icy objects or comets are in the outer region with the remainder in the relatively dense core.
		The Oort cloud is the source of long-period comets and possibly higher-inclination intermediate comets that were pulled into shorter period orbits by the planets, such as Halley and Swift-Tuttle.
	www.solarviews.com /eng/oort.htm (710 words)

	Jan Oort Bibliography
		Oort, J.H., “The Galaxy,” IAU Symposium 20, 1-9 (1964).
		Oort, J.H., “The Density of the Universe,”; Astronomy & Astrophysics 7, 405 (1970).
		Oort, J.H., “Structure of the Universe,”; in Early Evolution of the Universe and its Present Structure; Proceedings of the Symposium, Kolymbari, Greece, August 30-September 2, 1982, (Reidel, Dordrecht & Boston, 1983), 1-6.
	www.phys-astro.sonoma.edu /BruceMedalists/Oort/OortRefs.html (911 words)

	Oort, Jan Hendrik -- Encyclopædia Britannica
		After studies at the University of Groningen, Oort was appointed astronomer to the Leiden Observatory in 1924 and became director in 1945, a position he held until 1970.
		Named for the Dutch astronomer Jan Oort, who demonstrated its existence, the Oort cloud comprises objects that are less than 100 km (60 miles) in diameter and that number...
		A forerunner of the Reformation, Jan Hus of Bohemia was burned at the stake as a heretic rather than recant his religious views and his criticisms of the clergy.
	www.britannica.com /eb/article-9057161 (640 words)

	Oort, Jan Hendrik (Site not responding. Last check: 2007-10-08)
		In 1944 Oort's student Hendrik van de Hulst (1918-) calculated that hydrogen in space would emit radio waves at 21 cm/8.3 in wavelength, and in the 1950s Oort's team mapped the spiral structure of the Milky Way from the radio waves given out by interstellar hydrogen.
		Oort was born in Franeker, Friesland, and studied at Groningen.
		Oort confirmed the calculations of astronomers Bertil Lindblad and Harlow Shapley and went on to show that the stars in the Milky Way were arranged like planets revolving round a sun, in that the stars nearer the centre of th
	www.cartage.org.lb /en/themes/Biographies/MainBiographies/O/Oort/1.html (178 words)

	Planetary Society: Oort Cloud
		By using computer simulations of conditions in the Solar System 4.5 billion years ago, the researchers concluded that many of the objects that could have ended up in the Oort cloud were diverted from their course or ground to dust before they ever had a chance to reach their cloudy destination.
		In 1950 the Dutch astronomer Jan Hendrik Oort noted that the orbits of most observed comets are shaped like extremely elongated ellipses.
		Oort himself estimated that his cloud was composed of as many as 12 billion comets, and his estimate remains valid today.
	www.planetary.org /html/news/articlearchive/headlines/2001/Oort1.htm (957 words)

	Oort Cloud & Sol b?
		Oddly enough, Oort Cloud objects were probably formed in a region of the protoplanetary disk that was located closer to the Sun than the Edgeworth-Kuiper Belt objects that persist in the orbital plane of the planets (ecliptic) to this day.
		In addition, tidal forces affecting the Oort Cloud come from the differential gravitational forces exerted by stars in the Milky Way's galactic disk and by the galactic core on the Sun and comets as a result of their relative location in the Solar System.
		The Oort Cloud is the source of long-period comets and possibly higher-inclination intermediate comets, such as Halley and Swift-Tuttle, that were pulled into shorter period orbits by the planets (see schematic diagram of nomenclature and relationships among asteroids, Edgeworth-Kuiper bodies, and comets and their different subgroups by William K. Hartmann).
	www.solstation.com /stars/oort.htm (1999 words)

	ESA - Science - Home - Comet pioneer: Jan Hendrik Oort
		By the time of his death, at the age of 92, Professor Oort was recognised as one of the greatest astronomers of the 20th century.
		In the days before radio telescopes, Oort was one of the few scientists to realise the potential significance of using radio waves to search the heavens.
		Jan Hendrik Oort was a physician's son, born at Franeker, Friesland, and educated at Leiden Gymnasium and Groningen University, before going to the USA to study at Yale University.
	www.esa.int /esaSC/SEMBPC2PGQD_index_0.html (645 words)

	Astronomy & Space
		Comets, the Kuiper Belt, and the Oort Cloud In 1950 Jan Oort noticed that 1.no comet has been observed with an orbit that indicates that it came from interstellar space, 2.there is a strong tendency for aphelia of long period comet orbits to lie at.
		The Oort cloud and long period comets The significant number of long period comets (> 1000 years) and non-periodic comets led Jan Oort to speculate in 1950 that a cloud of objects surrounds the Solar System.
		Comet Reservoirs The Oort Cloud Based on the orbits of long period comets, in 1950 Jan Oort proposed that a distance, spherical distribution of cometary nuclei surrounding the solar system.
	groups.msn.com /AstronomySpace/kuiperbeltoortcloud.msnw (835 words)

	Encyclopedia: Jan Oort
		The Parkes 64 metre radio telescope in New South Wales, Australia (the bigger of the two shown) In contrast to an ordinary telescope, which produces visible light images, a radio telescope sees radio waves emitted by radio sources, typically by means of a large parabolic (dish) antenna, or arrays of...
		Comet Hale-Bopp, showing a white dust tail and blue gas tail (February 1997) A comet is a small body in the solar system that orbits the sun and (at least occasionally) exhibits a coma (or atmosphere) and/or a tail -- both due primarily to the effects of solar radiation...
		The Milky Way (a translation of the Latin Via Lactea, in turn derived from the Greek Galaxia Kuklos) is the galaxy in which the Earth is found.
	www.nationmaster.com /encyclopedia/Jan-Oort (1097 words)

	Oort Cloud solar system astronomy
		There is a strong tendency for the furthest points from the Sun (aphelia) of long-period comets to group at about 4.6 trillion miles (50,000 AU or 8/10 of a light-year) from the Sun.
		From these observations Oort proposed that (long-period) comets reside in an immense spherical cloud surrounding the planets and extending out about three light years from the Sun -- the boundary of the Sun’s influence.
		The Oort Cloud’s inhabitants are most strongly perturbed, however, by the tidal forces of giant molecular clouds.
	www.myastrologybook.com /Oort-Cloud-solar-system-astronomy.htm (495 words)

	ESA Science & Technology: 100th anniversary of comet pioneer's birth
		One of this select company was a Dutch astronomer, Jan Oort, who was born 100 years ago today.
		In the days before the advent of radio telescopes, Oort was one of the few scientists to realise the potential significance of using radio waves to search the heavens.
		According to Peter Wenzel, from the Solar System System Division at ESTEC in The Netherlands, Jan Oort was one of the few people able to boast that he had seen Halley's Comet on two separate apparitions.
	sci.esa.int /science-e/www/object/index.cfm?fobjectid=18385 (666 words)

	ASTR 1110 Lectures Spring 1999 (Site not responding. Last check: 2007-10-08)
		In 1950 Jan Oort analyzed the original orbits of 19 Long Period Comets (comets whose orbital periods exceed 200 years, usually by a lot).
		To supply the observed number of long period comets over the age of the solar system, the number of comets in the Oort Cloud must be on the order of 100 billion.
		This illustrated efforts to understand whether the Oort Cloud could also be the source of short period comets (sometimes also called Jupiter family comets).
	lasp.colorado.edu /~colwell/astr3750-f00/nov7notes.html (564 words)

	Specific Arguments - Comets
		During the 1980s, astronomers realized that Oort Cloud comets may be outnumbered by an inner cloud that begins about 3,000 AU from the Sun and continues to the edge of the classical Oort Cloud at 20,000 AU.
		Most estimates place the population of the inner Oort Cloud at about five to ten times that of the outer cloud say, 20 trillion or so although the number could be ten times greater than that.
		Oort determined that comets tossed into highly elliptical orbits by Uranus and Neptune would be nudged into more nearly circular orbits by encounters with passing stars.
	www.infidels.org /library/modern/dave_matson/young-earth/specific_arguments/comets.html (1681 words)

	The Bruce Medalists: Jan Oort
		Jan Oort, who worked at the University of Leiden from 1924 to 1992, began studying stellar dynamics under Jacobus C. Kapteyn at Groningen.
		Oort found evidence for differential rotation and founded the mathematical theory of galactic structure.
		Oort was a leader in European astronomy and played a major role in the rise of the European Southern Observatory and other international organizations.
	www.phys-astro.sonoma.edu /brucemedalists/oort/Oort.html (407 words)

Try your search on: Qwika (all wikis)