He had started to work as an assistant to
Johann 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 a
Fraunhofer-
refractor with 9
Zoll (~22.5 cm)
aperture. In 1838 he discovered an inner, dark ring of
Saturn. From 2 December 1839 to 6 March 1840 he discovered three new
comets. In 1845 Galle was awarded a
Dr. phil. His
doctoral thesis was a reduction and critical discussion of
Ole Rømer's observation of
meridian transits of
stars and
planets on the days from 20 October to 23 October 1706.
Discovery of Neptune Around the same time in 1845 he sent a copy of his thesis to
Urbain 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 the
perturbations of the orbit of the planet
Uranus 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 assistant
Heinrich Louis d'Arrest, Galle discovered a star of 8th
magnitude, only 1° away from the calculated position, which was not recorded in the
Berliner Akademischen Sternkarte. Over the next two evenings, a
proper 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 name
Neptune. Galle always refused to be acknowledged as the discoverer of Neptune; he attributed the discovery to Le Verrier. In 1847 Galle was designated as the successor to
Friedrich Wilhelm Bessel as Director of
Königsberg Observatory. Before the enacted nomination from
Friedrich Wilhelm IV effected
de facto, Galle withdrew his application at the beginning of 1848 due to an intrigue against him led by
Carl Gustav Jacob Jacobi. == Breslau Observatory ==