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Astro*Dictionary by Michael Erlewine





1 article for "Oort, Jan Hendrik"

Oort, Jan Hendrik [Astri*Index]

(28 April 1900 – 5 November 1992) Dutch astronomer. Born at Franeker, Friesland; died at Leiden, South Holland.

From the relative motion of nearby stars, he was able to derive a result which agreed with Shapley: that the center of our galaxy lay in the direction of the constellation Sagittarius. He calculated the distance to this center at 30,000LYs (light-years), and determined that the orbit of our solar system about it required some 200,000,000 years for each circuit. In 1950, he proposed an interesting theory concerning the origin of comets: At a distance of about 1LY, a vast cloud of minor planets (the Oort Cloud) are located in a huge asteroid belt. A few of these are continually hurled into the solar system by the gravitational perturbations of nearby stars. Whether or not his cloud exists, the theory has received serious attention.


See also: ♦ Shapley, Harlow


Astro*Index Copyright © 1997 Michael Erlewine