Johann Gottfried Galle (June 9, 1812 – July 10, 1910) was a German astronomer at the Berlin Observatory who, with help from Urbain Le Verrier, sighted Neptune on September 23, 1846.

He had started to work as an assistant to Johann Franz Encke in 1835 immediately following the completion of the Berlin observatory. in 1851 he moved to Breslau (now Wrocław) to become professor of astronomy and the director of the local observatory.

Throughout his career he studied comets, and in 1894 (with the help of his son Andreas Galle ) he published a list with 414 comets. He himself had previously discovered three comets in the short span from December 2,1839 to March 6,1840.

Craters on the Moon and Mars, and a ring of Neptune, were named in his honor.

First Neptune observation

Galle's Ph.D. thesis finished in 1845 was a reduction and critical discussion of Ole Rømer's observation of Uranus on the days from October 20 to October 23, 1706. Around 1845 he sent a copy of his thesis to Urbain Le Verrier, but only received an answer a year later on September 18,1846. It reached Galle on September 23 and in it Le Verrier asked him to look at a certain region of sky to find a predicted new planet, which would explain the perturbations of Uranus. The same night, after Encke gave him the permission against his own judgement, an object fitting the description was found, and it was confirmed as being a planet over the next two evenings.

External links

Obituaries

• AN 185 (1910) 309/310 (in German)
• JRASC 4 (1910) 379
• MNRAS 71 (1911) 275
• Obs 33 (1910) 314 (not online)