We have visited all the planets of solar system and found worlds orbiting distant stars. Now we're about to explore ... Pluto? If you find yourself asking, "So what?" you're not alone. But you might be surprised by the answer.
The Search Begins
In 1929, a young researcher named Clyde Tombaugh was handed a thankless, seemingly impossible task.
His bosses at the Lowell Observatory in Flagstaff, Arizona, gave him a series of nearly identical pictures of the same part of the night sky taken a few days apart and asked him to search, with his naked eyes, for a speck of light that moved like a planet. These were not pretty photos, and they barely changed from day to day. So we can only imagine how daunting this assignment must have felt for the young Tombaugh. Yet he took it graciously and spent over a year comparing photographs, two by two, using only an antiquated mechanical device called a blink comparator, his bare eyes, and his knowledge of planetary movement.