The Discovery of a Planet, Part 1: The Blinking Image

Posted by Amir Alexander on 2005/02/12 11:00 CST

February 18, 1930, was a cloudy day at the Lowell Observatory, on top of Mars Hill in Flagstaff, Arizona. 22 year old Clyde Tombaugh was hard at work, peering through the lens of an ancient-looking brass-colored device. The instrument, known as a “blink comparator,” mounted two large photographic plates.

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