- Dutch astronomer Jan H. Oort (1900 AD - 1992 AD) in 1950 proposed that a spherical region around our solar system contained several hundred billion comets. The Oort Cloud is a great distance from our solar system, about 40,000 to 60,000 AU. As stars pass near the Oort cloud, their gravity knocks some of the comets from their stable orbit, and sends them toward the Sun. This is the source of most Long Period Comets.
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Oort cloud — in reference to the hypothetical cloud of small objects beyond Pluto that become comets, proposed 1949 by Dutch astronomer Jan Hendrick Oort (1900 1992), and named for him by 1968 … Etymology dictionary
Oort cloud — [ôrt] n. [after J. Oort (1900 92), Du astronomer] a moving mass of icy cosmic debris thought to exist in the vast region beyond Pluto and to be the source of the comets that orbit the sun … English World dictionary
Oort cloud — An artist s rendering of the Oort cloud and the Kuiper belt (inset). Sizes of individual objects have been exaggerated for visibility … Wikipedia
Oort cloud — /awrt, ohrt/, Astron. a region of the solar system far beyond the orbit of Pluto in which billions of comets move in nearly circular orbits unless one is pulled into a highly eccentric elliptical orbit by a passing star. [1975 80; after Dutch… … Universalium
Oort cloud — noun (astronomy) a hypothetical huge collection of comets orbiting the sun far beyond the orbit of Pluto; perturbations (as by other stars) can upset a comet s orbit and may send it tumbling toward the sun • Topics: ↑astronomy, ↑uranology •… … Useful english dictionary
Oort cloud — noun Etymology: Jan Oort died 1992 Dutch astronomer Date: 1974 a spherical shell of cometary bodies believed to surround the sun far beyond the orbit of Pluto and from which some are dislodged when perturbed (as by a passing star) to fall toward… … New Collegiate Dictionary
Oort Cloud — noun A roughly spherical region of space from 50,000 to 100,000 astronomical units (approximately 1 light year) from the sun; supposedly the source of most comets … Wiktionary
Oort, Jan Hendrik — ▪ Dutch astronomer born April 28, 1900, Franeker, Neth. died Nov. 5, 1992, Leiden Dutch astronomer who was one of the most important figures in 20th century efforts to understand the nature of the Milky Way Galaxy. After studies at… … Universalium
Oort , Jan Hendrik — (1900–1992) Dutch astronomer The son of a physician from Franeker in the Netherlands, Oort (ohrt) was educated at the University of Gröningen where he worked under Jacobus Kapteyn and gained his PhD in 1926. After a short period at Yale… … Scientists
cloud — cloudlike, adj. /klowd/, n. 1. a visible collection of particles of water or ice suspended in the air, usually at an elevation above the earth s surface. 2. any similar mass, esp. of smoke or dust. 3. a dim or obscure area in something otherwise… … Universalium