Clyde Tombaugh 6

Tell me about the day that you actually discovered the planet Pluto.

Clyde Tombaugh: I did not know that I had recorded the image of Pluto on those plates, not until I scanned them later in February. You passed your gaze over all these stars that you have to be conscious of seeing every star image, because you don't know which one's going to shift, if they shift. It's very tedious work and you go through tens of thousands of star images. I came to one place where it actually was, turned the next field and there it was! Instantly, I knew I had a planet beyond the orbit of Neptune because I knew the amount of shift was what fitted the situation. That was the most instantaneous thrill you can imagine. It just electrified me!