There is an undeniable thrill in seeing this distant member of the Sun's family, and Solar System buffs cannot call their observations complete without it.
Percival Lowell, best known for his theories about Martian life, began the search for Pluto in 1905.
An accomplished mathematician, he believed that residual irregularities in the motion of Uranus could be explained by the gravitational pull of a planet orbiting beyond Neptune. Lowell's approach had good precedent: discrepancies in Uranus's motion had led directly to the discovery of Neptune in 1846.
However, in the case of Pluto, Lowell was off track— we now know that the real Pluto is much too small to have any such effect. But Lowell's obsession with "Planet X," as he called it, did eventually pay off. After Lowell's death in 1916, the observatory he founded in Flagstaff, Arizona, dropped the search for more than a decade. Then in 1929, Lowell Observatory hired Clyde Tombaugh, a 26-year-old amateur astronomer from Kansas. He started making a photographic survey of the ecliptic—and, working systematically, he found the planet within a year. It was named Pluto for the Roman god of the underworld.