Lowell Observatory, Arizona

Established in 1894, Lowell Observatory is comprised of multiple observatories spread across Mars Hill, Anderson Mesa (10 miles away), and other hills in the Flagstaff area. This observatory is known for its observations of the solar system and of asteroids, though it also explores objects in deeper space. There are extensive educational displays in the visitors center. Astronomer Clyde Tombaugh discovered the planet Pluto in 1930, while working at Lowell.