Neptune
After the discovery of Uranus, it was noticed that its orbit
was not as it should be in accordance with Newton's laws.
It was therefore predicted that another more distant planet
must be perturbing Uranus's orbit. Neptune was first observed
by Galle in 1846 in exactly the spot independently predicted
by Adams and Le Verrier from calculations based on the observed
positions of Jupiter, Saturn and Uranus. An international
dispute arose between Adams and Le Verrier over priority and
the right to name the new planet; they are now jointly credited
with Neptune's discovery. Subsequent observations have shown
that the orbits calculated by Adams's and Le Verrier's diverge
from Neptune's actual orbit fairly quickly. Had the search for
the planet taken place a few years earlier or later it would
not have been found anywhere near the predicted location.