Neptune is the eighth planet from the Sun and the most remote of the gas giants of the outer solar system. Independently of each other, in 1845, John Couch Adams and Urbain Jean Joseph Leverrie calculated where an eighth planet in the solar system would have to be in order to explain slight perturbations in the orbit of Uranus. On September 23, 1846, Johann Gottfried Galle and Heinrich Louis d'Arrest found a new planet within one degree of the position sent to them by Leverrier. The prediction made by Adams a year earlier was not published until after is discovery because of the skepticism of his findings.
During the months following the announcement of the discovery, an international controversy developed between the two astronomers as to whom credit belonged and what the planet should be named. They agreed to name the new planet Neptune, for the Roman sea god, and credit was given to both Adams and Leverrier for their calculations. Galileo may have spotted this planet two centuries earlier but never actually recognized it as a planet.