Instantly, I knew I had a planet beyond the orbit of Neptune....
In 1926, Clyde Tombaugh built his first telescope, but the quality was poor. He began to read Scientific American, and a book called Amateur Telescope Making, so by the time he made his third, things were working much better. It was his third telescope, with which he used to make drawings of markings on Jupiter and Mars. And it was these drawings with which he got a job at the Lowell Observatory in Flagstaff, Arizona; the only planetary observatory in the country at the time.
At Lowell, Tombaugh was assigned to take photographs at night with the telescope. On successive nights, he would photograph the same area and then examine the plates to see if there was any change that occurred in the star field. Since the plates would have several hundred images, it was a very tedious and awesome responsibility to see if he could detect which, from all those images, moved. It was in February of 1930, that he finally got around to examining plates taken a month before. And, it was on the 18th of February,around 4 o'clock in the afternoon, when he realized in a "second's flash, that I had made a great discovery", and indeed he had. He discovered the planet Pluto.
Clyde Tombaugh was born in 1906, in Streator, Illinois. Raised on a farm in western Kansas, Tombaugh was self taught in astronomy, geometry, and trigonometry. He had no formal training and only went to college AFTER he made his discovery. He earned his Bachelor's in 1936 and his Master's in '38, from the University of Kansas. During his years at Lowell, he discovered hundreds of new variable stars, new asteroids, and two comets. In all, he counted over 29,000 galaxies. He taught navigation to the U.S. Navy at Arizona State from 1943 to 1945.
After WWII, He worked for the White Sands Missile Range in Las Cruces, New Mexico, supervising optical instrumentation used in missile testing. He designed a super camera called the IGOR (Intercept Ground Optical Recorder), which remained in use and unimproved on for 30 years. He taught at New Mexico State University from 1955 until his retirement in 1973. In retirement , he traveled the country giving lectures to raise money for a scholarship fund for post-doctoral students in astronomy. He died in Las Cruces in 1997, shortly before his 91st birthday.