Discovery of Neptune

Neptune was identified at the Berlin Observatory, where Johann Galle and his student Heinrich d'Arrest found it within about one degree of the position predicted by the French mathematician Urbain Le Verrier. The search had been prompted by unexplained deviations in the orbit of Uranus, which suggested the gravitational pull of an unseen planet. The English mathematician John Couch Adams had made similar calculations earlier, and a bitter dispute over priority followed, although both men are now generally credited. Neptune was the first planet located through mathematical prediction rather than chance observation, a striking confirmation of Newtonian gravitation. Its large moon Triton was found only a few weeks later by the English brewer and astronomer William Lassell.

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