On February 18, 1930, Planet X was discovered by Clyde Tombaugh when he worked at the Lowell Observatory in Flagstaff, Arizona. He didn't have a University degree, but at the time was a talented amateur astronomer. Tombaugh’s number one job was to make and search photographic plates of the sky, looking for anything that might shift its position from one night to the next, as seen when comparing one photo to another picture of the same part of the sky taken a few nights later. It was painstaking work, but rewarding; Planet X was discovered out in the direction of the constellation Gemini, which is well up in the eastern sky after sunset tonight. But Planet X isn’t there anymore. This distant world is now six constellations over to the east, in Sagittarius. Oh, and it’s not called Planet X anymore; shortly after its discovery it was renamed Pluto.