Johann Gottfried Galle (9 June 1812 – 10 July 1910) was a German
astronomer from Radis, Germany, at the
Berlin Observatory who, on 23 September 1846, with the assistance of student
Heinrich Louis d'Arrest, was the
first person to view the planet Neptune and know what he was looking at.
Urbain Le Verrier had predicted the existence and position of Neptune, and sent the coordinates to Galle, asking him to verify. Galle found Neptune in the same night he received Le Verrier's letter, within 1° of the predicted position. The discovery of Neptune is widely regarded as a dramatic validation of
celestial mechanics, and is one of the most remarkable moments of 19th century science.