Much like the discovery of Pluto, the search for a planet beyond Uranus began when mathematical calculations indicated that the orbit of Uranus did not behave in the way according to Newton's laws. Thus, astronomers concluded that there had to be a planet beyond Uranus because of a distortion in the planet's orbit. They were correct. On September 23, 1846, Johann Gottfried Galle (of the Berlin Observatory) and Louis d'Arrest (student of astronomy) became the first two people to observe the planet Neptune. They were successful not because they searched the entire heavens randomly, but by basing their observations around the area that Neptune was predicted to be. Urbain Jean Adams and Joseph Le Verrier had calculated where Neptune would be based on observations of Jupiter, Saturn and Uranus. It was fortunate that Galle and d'Arrest had scanned the skies within a small time margin from which the predicted locations were made. Neptune departs from the predicted orbit rather quickly and the planet would not have been found if the two astronomers had procrastinated (you see what could happen if you do?).
After Neptune was discovered, the English and French battled over the right to name the planet, but in the end, credit for discovery was given to both sides.
The Discovery of Neptune 
