If we decide on a definition of planet that Pluto fails to meet, making it a Kuiper Belt Object instead, doesn't that mean that Tombaugh, rather than finding the latest (1) of a known catagory of bodies, instead is the man who found the very first example of a new class of world? That would put him in the company of people like Galileo (Who first recorded moons of worlds other than Earth) and Giussepe Piazzi (who discovered the first recorded asteroid, Ceres).
1: Unless we settle on a definition that includes 2003 UB 313, in which case Tombaugh's is just one of the more recently discovered planets.
1: Unless we settle on a definition that includes 2003 UB 313, in which case Tombaugh's is just one of the more recently discovered planets.