Galle, Johann Gottfried (1812–1910)

German astronomer. He located the planet Neptune in 1846, close to the position predicted by French mathematician Urbain Leverrier and the English astronomer J C Adams.

Galle was born at Pabsthaus, near Wittenberg, Prussia, and educated at Berlin. He worked at the Berlin Observatory until 1851, when he became professor of astronomy and director of the Breslau Observatory (now in Wrocław, Poland).

In 1846, Galle received from Leverrier, director of the Paris Observatory, the calculation of the position of a new planet, predicted mathematically from its apparent gravitational effect on Uranus, then the outermost known planet. Within one hour of beginning their search 25 September, Galle and his colleague Heinrich d'Arrest (1822–1875) had located Neptune, less than 1° away from the predicted position.

Galle suggested a method of measuring the scale of the Solar System by observing the parallax of asteroids, first applying his method to the asteroid Flora in 1873. The method was employed with great success after Galle's death.