Lowell Observatory

On Mars Hill, above a railroad town that happened to have dark skies and enough elevation to matter, Percival Lowell built an observatory in 1894 to chase his theory of Martian canals. He was wrong about Mars. But the institution he funded — staff salaries and all — became one of the most consequential in American astronomy. Clyde Tombaugh discovered Pluto here in 1930. Vesto Slipher's data on receding galaxies helped Edwin Hubble explain an expanding universe. Astronauts came to map the Moon. The 24-inch Clark Refracting Telescope, built in 1896, still takes visitors to the eyepiece.