November 1, 2014

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Don't Believe Everything On the Big Screen

video from PATHE Pictorial (1934)

George Tarsoudis posted links on his Facebook wall to some 1930s movies about the Moon. This one, with a very tony British announcer, gives the origin of the Moon theory from George Darwin, grandson of Charles. George, the British one, proposed that the early Earth spun so fast that it elongated into a bowling pin shape, and the rapidly rotating top ball fissioned off, becoming the Moon. This was one of three competing theories of the Moon during the first half of the 20th century; but few people were pleased by any of lunar theory until the giant impact idea emerged in the mid-1970s. The other two theories were the capture theory - an errant object came too close to the Earth and was gravitationally captured, and the co-accretion idea - the Moon and the Earth formed from the same part of the solar nebula. I think it was cosmo-chemist Harold Urey who called these the daughter (fission), spouse (capture), and sister (co-accretion) theories. I wonder if a female astronomer would have called them the son, spouse and brother theories? When you finish enjoying this theoretical news film, check out this one from 1932 that is purely observational. It is from the University of Michigan where Robert McMath used changing shadow lengths from films to determine the depths of lunar craters. Thanks, George (the Greek one).

Chuck Wood

Yesterday's LPOD: Deorbiting

Tomorrow's LPOD: Upside Down


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