A theory of the formation of the Sun\u2019s planetary system advanced by Pierre Simon Laplace (1749-1827) in his Exposition du Systeme du Monde (1796). He theorized that gravity would condense a rotating disc of matter with most of its mass near the center into a massive central body and a number of much smaller orbiting planets. The theory gave a plausible explanation of why all the planets orbit in the same direction and why their orbits are in approximately the same plane.<\/p>\n
In 1873, James Clerk Maxwell (1831-79) showed theoretically that radiation would exert a pressure on any surface on which it fell. This was confirmed experimentally in 1900. Sunlight, for example, is calculated to exert a pressure of about 2 pounds per square mile, so small as to be difficult to measure. But in the interior of stars and galaxies where the radiation intensity is much higher, radiation pressure is a significant factor. In 1900 two scientists in the University of Chicago showed that the Maxwell radiation pressure in a disc of the size required in the nebular hypothesis would counterbalance the gravitational forces and prevent condensation; they advanced an alternative theory. Sir James Jeans later showed that the radiation-pressure difficulty only held for astronomically small aggregations such as the solar system and that the nebular hypothesis could explain the condensation of stars from a galactic disc.<\/p>\n
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A theory of the formation of the Sun\u2019s planetary system advanced by Pierre Simon Laplace (1749-1827) in his Exposition du Systeme du Monde (1796). He theorized that gravity would condense a rotating disc of matter with most of its mass near the center into a massive central body and a number of much smaller orbiting […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[14],"tags":[],"class_list":["post-211088","post","type-post","status-publish","format-standard","hentry","category-n"],"yoast_head":"\n