MMT Observatory MMT Observatory The MMT Observatory (MMTO) is an astronomical observatory on the site of Fred Lawrence Whipple Observatory (IAU observatory code 696). The Whipple observatory complex is located on Mount Hopkins, Arizona, US (55 km south of Tucson) in the Santa Rita Mountains. The observatory is run by the University of Arizona and the Smithsonian Institution, and has a visitor center in nearby Amado, Arizona. The MMTO is the home of the MMT (formerly Multiple Mirror Telescope), which currently has a primary mirror 6.5 m in diameter. The name originally comes from the fact that the light gathering for the
Percival Lowell Planet X. Lowell started a search program in 1906 using a camera in aperture. The small field of view of the reflecting telescope rendered the instrument impractical for searching. From 1914 to 1916, a telescope on loan from Sproul Observatory was used to search for Planet X. Lowell did not discover Pluto but later Lowell Observatory (observatory code 690) would photograph Pluto in March and April 1915, without realizing at the time that it was not a star. In 1930 Clyde Tombaugh, working at the Lowell Observatory, discovered Pluto near the location expected for Planet X. Partly in recognition of