Small changes in the movement of Neptune led several astronomers to believe that an undiscovered planet was affecting Neptune's orbit.

VOA: special.2010.07.11

A British astronomer named John Couch Adams had also predicted Neptune's position in space.

VOA: special.2011.07.27

Unidentified Man: Is Neptune a planet, because everybody knows that Neptune's orbit is crossed by Pluto's.

NPR: Pluto, the Un-Planet?

Its elliptical orbit actually crosses Neptune's path, yet the timing of the two planets' respective motions ensures that, like figures in a clockwork model, they never collide.

ECONOMIST: Unbuckling the Kuiper belt

Unlike the long-lived storms of Jupiter, one of which (the Great Red Spot) has been tracked continously by observers for many decades, Neptune's spots seem to be relatively short-lived.

ECONOMIST: Comparative meteorology