Francis G. Pease

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Francis Gladheim Pease (January 14, 1881 – February 7, 1938) was an American astronomer and instrument maker. He worked at Yerkes Observatory in Wisconsin as an observer and optician, helping George W. Ritchey build some of the first large American reflecting telescopes. In 1908 he moved to Mount Wilson Observatory, where he designed and built instruments, including the 100-inch telescope and a 50-foot interferometer used to measure star sizes. His high-quality Moon photographs helped Gene Shoemaker create the first geological map of the Moon. He was a longtime assistant to Albert A. Michelson, and in 1920 the two used a Michelson stellar interferometer on the Mount Wilson 100-inch telescope to measure Betelgeuse’s angular diameter, finding about 0.047 arcseconds, close to Eddington’s prediction. Pease later helped design the 200-inch Hale Telescope at Mount Palomar Observatory. In 1928 he discovered the first planetary nebula inside a globular cluster, now called Pease 1. The Moon crater Pease is named after him.