Discovery of Neptune

On September 23, 1846, astronomer Johann Gottfried Galle and student Heinrich Louis d'Arrest observed Neptune from the Berlin Observatory, locating it within one degree of the position predicted by French mathematician Urbain Le Verrier. Le Verrier and English mathematician John Couch Adams had independently calculated the planet's location by analyzing unexplained irregularities in the orbit of Uranus. Neptune became the first planet discovered through mathematical prediction rather than direct observation, confirming Newtonian gravitational theory applied beyond the then-known solar system.