The Night I Discovered Pluto

Just what would one expect Clyde W. Tombaugh to do the night of Feb. 18, 1930 when the 24 year-old amateur astronomer ended decades of speculation and found the far away planet? Not what he did, but let’s back up. The Lowell Observatory outside Flagstaff, Arizona was founded by Percival Lowell of Boston in 1894 to study Mars. But Lowell became convinced there was another planet out there somewhere, “Planet X,” and searched for it until his death in November of 1916. In 1929, with a larger telescope, the observatory hired a Kansas boy named Clyde Tombaugh to continue the work. It was a tedious job, studying photographic plates taken by the telescope, sometimes filled with hundreds of thousands of stars, looking for one that moved like a planet. And then he found it, on plates that were three weeks old. Tombaugh rushed to tell the observatory’s honchos, who were awestruck at the evidence. Of course, they immediately wanted to rephotograph the area, but on looking out the window, Tombaugh remembers, “The sky was very cloudy, and much snow was on the ground.”

So what to do? As he explained in an article republished in “Arizona Memories,” he recalls this: “It was now 6:00 p.m., an hour later than my usual departure to drive down Mars Hill to eat dinner in a cafe and pick up the observatory mail at the post office. The sky was still hopelessly cloudy. Instead of driving back up to the observatory, I decided to attend a movie. It was Gary Cooper in The Virginian.” So that’s what you do the night you discover a planet, which, by the way, was only six degrees from where Percival Lowell thought it would be.