Patience on the part of young Clyde Tombaugh, an assistant astronomer, is what led him finally to discover the dwarf "planet" Pluto. For over seven decades, Pluto was considered the ninth planet of our solar system. Astronomers had already calculated a probable orbit for this “suspected” heavenly body, which they had never seen. But Tombaugh took up the search in March 1929. He examined scores of telescopic photographs, each showing tens of thousands of star images in pairs under the blink comparator, or dual microscope. It often took three days to scan a single pair of photographs. It was exhausting, eye-cracking work, in Tombaugh’s own words, “brutal, tediousness.” The search went on for months. Star by star, Tombaugh examined twenty million images. Finally, on February 18, 1930, as he was blinking a pair of photographs in the constellation Gemini, “I suddenly came upon the image of Pluto!” It was the most dramatic astronomic discovery in nearly one hundred years and it was made possible by patience.