Francis Gladheim Pease

Francis Gladsheim Pease ( born January 14, 1881 in Cambridge, Massachusetts, † February 7, 1938 in Pasadena, California ) was an American astronomer.

Pease was born in Cambridge, MA. His parents soon moved to Illinois, so he attended high school in Highland Park and then studied in Chicago at the Armour Institute of Technology.

In 1901 Pease worked at Yerkes Observatory. He studied there under G.W. Ritchey optical design and manufacturing process. He gained practical experience in instrument, was active but also as an astronomical observer with the 24 -inch reflector of the Observatory.

1904 Pease went together with G. E. Hale and Ritchey to Pasadena to construct the newly founded Mount Wilson Observatory. Together with Ritchey, he constructed most of the new features of the observatory. He was partially responsible for the construction of the Snow telescope, the 60-foot or 150 -foot tower telescope, and the 60 -inch reflector. He took the largest share of the construction of the 100 -inch reflector. In particular, he oversaw design and testing of the larger telescope mirrors.

Also on the Mount Wilson Pease served as observers: observed with the 60 -incher and he photographed nebulae and star clusters. He performed spectroscopic measurements, which led extragalactic nebula for the initial observation of the rotation among others. With the 100 -inch model he made moon photographs that contributed to the creation of a photographic map of the moon.

Pease assisted A. A. Michelson in 1920 when the first successful measurements of stellar diameters with the aid of an interferometer. Michelson had found that even the 2.5 m opening of the 100 -inch model was not sufficient as interferometric to determine the diameter of Betelgeuse. They brought in this telescope, therefore a 20 feet (6 meters) long interferometer on, carried which small at both ends mirrors and so enlarged the base width. They were able to reduce the diameter of Betelgeuse as 0.047 " to determine ± 10 % (consistent with the modern value 0.0566 " ± 0.0010 "). Was followed by measurements at several other bright stars. Pease led with these investigations later 50-foot interferometer continued.

As Michelson in the years 1924-1928 repeated his earlier measurements of the speed of light, Pease assisted him in the construction of the measuring apparatus and in carrying out the observations. Another, which began in 1930 and ended in 1934 repeating these measurements using a mile-long evacuated tube led Pease because of the illness Michelson largely by themselves.

In 1929 Pease repeated the ether drift experiment of Michelson and Morley with a path length of 85 feet and also received a negative result.

Pease studied design principles for very large telescopes. After it was started in 1930 to work on the 200 -inch Hale telescope on Palomar Observatory, he devoted half his time these engineering designs.

1928 Pease discovered the first located in a globular cluster planetary nebula, Pease 1, which was later named after him. A moon crater 38 km in diameter has been named after him.