Even more amazing that it was found in the era it was. People were pouring over the skies looking for the next big planet, and instead they found this little guy.

There are still some orbital dynamics suggestions that something large and dark is lurking out there -- an ice giant. But it's still largely conjecture. It'd be interesting to see how they define it should they find something very large (say Neptune mass), but it hasn't cleared its orbit. Is it a planet or not? :D