C. Tombaugh; Astronomer Found Pluto

LAS CRUCES, N.M. — Clyde W. Tombaugh, discoverer of the planet Pluto, has died at his home in New Mexico. He was 90.

Tombaugh discovered Pluto in 1930, when he was a budding 23-year-old scientist with only a high school diploma. He died Friday after suffering from years of respiratory problems.

A self-taught astronomer who made his own 9-inch telescope in the 1920s on his family’s farm in Kansas, Tombaugh drew sketches of Mars and Jupiter and mailed them to the Lowell Observatory in Tucson, Arizona, asking for scientists’ feedback on his work.

Instead, he was offered a job helping scientists search for Planet X, which astronomer Percival Lowell believed was the solar system’s ninth planet. Lowell and others had noticed wobbles in the orbits of Neptune and Uranus, indicating that they were being tugged by the gravity of another planet.

Over 10 months, Tombaugh worked an estimated 7,000 hours poring over two 14-by-17 inch photos, taken several days apart, of the night sky. He figured that if a planet was visible, it would have moved to a new position in the second photograph.

He finally found Planet X, later named Pluto, on Feb. 18, 1930, becoming one of only four people ever credited with discovering a planet.

“It was tedious, but it was much more interesting than farming, as far as I was concerned,” Tombaugh told Reuters in an interview last year.

Tombaugh later worked for the Navy and NASA before becoming a professor at New Mexico State University, where he retired in 1973.

He is survived by his wife, Patsy, two children and several grandchildren and great-grandchildren.