Johann Gottfried Galle, 1880Memorial plaque inWittenberg
Johann Gottfried Galle (9 June 1812 – 10 July 1910) was a Germanastronomer from Radis, Germany, at theBerlin Observatory who, on 23 September 1846, with the assistance of studentHeinrich Louis d'Arrest, was thefirst 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.[1] 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 ofcelestial mechanics, and is one of the most remarkable moments of 19th-century science.
Galle was born in thePapsthaus (a house in the Pabst wood) 2 km west ofRadis in the vicinity of the town ofGräfenhainichen, as the first son of Marie Henriettenée Pannier (1790–1839) and Johann Gottfried Galle (1790–1853),[2] an operator of a tar oven. He attended the Gymnasium inWittenberg and studied atFriedrich-Wilhelms-Universität Berlin from 1830 to 1833. He became a teacher at the Gymnasium inGuben, teaching mathematics andphysics. Later on, he transferred to the Gymnasium in Berlin.
He had started to work as an assistant toJohann Franz Encke in 1835 immediately following the completion of the new Berlin Observatory. Galle worked there for the next 16 years, making use especially of aFraunhofer-refractor with 9 Zoll (~22.5 cm)aperture. In 1838 he discovered an inner, dark ring ofSaturn. From 2 December 1839 to 6 March 1840 he discovered three newcomets.
The 9" refractor telescope which Galle used to discover Neptune
Around the same time in 1845 he sent a copy of his thesis toUrbain Le Verrier, but only received an answer a year later. Sent on 18 September 1846, it reached Galle on the morning of 23 September. Le Verrier had been investigating theperturbations of the orbit of the planetUranus and from this he derived the position of a still undiscovered planet, and requested Galle to search in the corresponding section of sky. The very same night (after Encke gave permission to search, against his own judgement), in collaboration with his assistantHeinrich Louis d'Arrest, Galle discovered a star of 8th magnitude, only 1° away from the calculated position, which was not recorded in theBerliner Akademischen Sternkarte. Over the next two evenings, aproper motion of the celestial object of 4 seconds of arc was measured, which determined it absolutely as a planet, for which Le Verrier proposed the nameNeptune. Galle always refused to be acknowledged as the discoverer of Neptune; he attributed the discovery to Le Verrier.
In 1851 he moved toBreslau (todayWrocław) to become the director of the local observatory, and in 1856 he became Professor of Astronomy at theSchlesischen Friedrich-Wilhelms-Universität Breslau. He worked in Breslau for over 45 years. For the academic year 1875/76 he was electedRector.[4] At Breslau he dealt with the exact determination of planetaryorbits and developed methods for calculating the height of theaurorae and the path ofmeteors, and consolidated the data for all 414 comets discovered up to 1894 into one work (with the help of his son). Otherwise he concerned himself with theEarth's magnetic field andclimatology. Altogether he published over 200 works.
In 1897 Galle returned toPotsdam, where he died in 1910 at the age of 98. He was survived by his wife and two sons, Andreas Galle and Georg Galle (1860–1946).
The town ofGräfenhainichen, which is close to his birthplace, erected a memorial to him in 1977.
In Breslau (today Wrocław) itself, it was commemorated by naming one of the streets with his last name – Gallestrasse. This name was in force until the end of World War II. Its contemporary name is Wapienna (meaningLimestone in Polish) Street.[5][6]
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