AAS 201st Meeting, January, 2003
Session 21. Planetary Systems: Instrumentation and Surveys
Poster, Monday, January 6, 2003, 9:20am-6:30pm, Exhibit Hall AB

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[21.16] Four Big-Telescope Planetary Astronomers of the 1920's at Mount Wilson, Yerkes, and Lick Observatories

D. E. Osterbrock (UCO/Lick Obs./UCSC)

Contrary to current mythology, many professional astronomers tried to do planetary research before World War II, as Ronald Doel and I have previously emphasized. Their difficulty was that once the known planets had been studied with the biggest and best telescopes, spectrographs, and radiometers there was little more they could do until some new instrumental development came along, and these were rare in those years.

Two astronomers who observed planets in the 1920's were Frank Ross, of the Yerkes Observatory faculty, with the Mount Wilson 60- and 100-inch telescopes, and William H. Wright, at Lick, with its 36-inch Crossley reflector, which he considered a big telescope. Both were keenly interested in photographic emulsions (Ross had been a research physicist at the Eastman Kodak Laboratory), and when fast new panchromatic films and plates became available in the 1920's they quickly applied them to photographing the planets. Robert J. Trumpler, also at Lick, used its 36-inch refractor in a combination of photographic (in the yellow and red spectral regions) and visual observing to map and describe Martian surface features. All three of them began planetary observing at the close opposition of Mars in 1924; they were all mainline scientists who ultimately were elected to the National Academy of Sciences. All three of them were doing descriptive work, seeing what was there, and none of them had any theoretical ideas to check or disprove. Francis G. Pease, more of a telescope designer and engineer at Mount Wilson, also used its 60- and 100-inch reflectors, chiefly to take photographs of the planets for illustrations in books and magazines. They all used fine-grain photographic plates, but seeing was a problem they could not overcome. Examples of their planetary photographs, papers, and letters will be posted. Ross and Trumpler dropped out of planetary astronomy after 1928, but Wright and Pease continued in it for many years.

An interesting sidelight is that Gerard P. Kuiper, as a young postdoc at Lick, co-authored his first planetary paper in English with Wright (on Mars).

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