In 1894 Boston businessman, author, and scientist Percival Lowell founded this observatory from which he studied Mars. His theories of the existence of a ninth planet sowed the seeds for the discovery of Pluto at Lowell in 1930 by Clyde Tombaugh. The 6,500-square-foot Steele Visitor Center hosts exhibits and lectures and has a gift shop. Several interactive exhibits—among them Pluto Walk, a scale model of the solar system—appeal to children. Visitors are invited, on some evenings, to peer through the 24-inch Clark telescope and the McAllister, a 16-inch reflector telescope. Day and evening viewings are offered year-round, but call ahead for a schedule. The Clark observatory dome is open and unheated, so dress for the outdoors. To reach the observatory, less than 2 miles from downtown, drive west on Route 66, which resumes its former name, Santa Fe Avenue, before it merges into Mars Hill Road.