Lowell Observatory
National Historic Landmark; In Flagstaff, The First International Dark Sky City (2001) · Flagstaff, Arizona
A working astronomical observatory on Mars Hill above Flagstaff, founded in 1894 by Percival Lowell to study Mars. Here Vesto Slipher measured the motions of galaxies that became key evidence for an expanding universe, and in 1930 Clyde Tombaugh discovered Pluto. Visitors tour the 1896 Clark Telescope and the Pluto Discovery Telescope, and after dark look through six telescopes on the Giovale Open Deck Observatory. It is a National Historic Landmark in Flagstaff, which in 2001 became the world's first International Dark Sky City. Cloudy nights limit the telescopes, so the visit is timed around the weather.
1400 West Mars Hill Road, Flagstaff, Arizona, 86001, United States
Open Monday and Wednesday to Sunday, 12 PM to 10 PM; closed Tuesdays (2026). Telescope viewing after dark, weather permitting. Check lowell.edu.
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