Final answer:
Percival Lowell played a significant role in the search for Pluto by founding the Lowell Observatory and advocating the notion of Planet X, but Clyde Tombaugh is the astronomer credited with Pluto's actual discovery.
Step-by-step explanation:
While Percival Lowell made significant contributions to the search for a ninth planet and established the ideal conditions for Pluto's discovery by founding the Lowell Observatory, he is not credited with the actual discovery of Pluto itself. That distinction goes to Clyde Tombaugh, a young observing assistant, who identified Pluto in 1930 by comparing photographs he had taken at the Lowell Observatory. The search for Planet X, motivated by observed deviations in Uranus' orbit, was Lowell's passion, and although his calculations were later proven incorrect, they set the groundwork that led to Pluto's discovery. The naming of Pluto, with an initial P-L honoring Percival Lowell, is an homage to his dedication and efforts in this astronomical venture.