Theodor Johan Christian Ambders Brorsen (29 July 1819 – 31 March 1895) was a Danish astronomer. He is best known for his discovery of five comets, including the lost periodic comet, 5D/Brorsen, and the periodic comet 23P/Brorsen-Metcalf.
Theodor Johan Christian Ambders Brorsen was born in Nordborg on the island Als, (South Jutland), as son of the captain Christian August Brorsen (1793-1840) and Annette Margrethe Gerhardine Schumacher (1788-1855). He got his three middle names after the maternal grandfather of his mother, the Nordborg counsel Johan Christian Ambders (1710-1795). After the amicable divorce of his parents in 1822, Brorsen grew up at his mother's. Her good financial circumstances allowed him to attend the school of the Moravians in Christiansfeld (1826-1829) and then, from 1830 to 1839, the Latin school in Flensburg. By request of his mother, Brorsen studied law in Kiel (1839), Berlin (1840), Heidelberg (1841), and again in Kiel (1842), until he decided to follow his inclinations and studied astronomy in Kiel in 1844.
Brorsen worked at the astronomical observatory of Kiel in 1846, and at the Altona Observatory in 1847. He rejected a job offer from the astronomical observatory "Rundetaarn" (Round tower) in Copenhagen. Instead, he accepted a job at the private observatory of baron John Parish (1774-1858, an Englishman, also known as Freiherr von Senftenberg) in Žamberk (at the time called Senftenberg) in the present-day Czech Republic. When the post of the director of the astronomical observatory of Altona became vacant in 1854, Brorsen applied to it, but was not chosen. After the death of baron Parish in 1858, his heirs had the observatory of Senftenberg dismantled and the astronomical instruments were sold, although Brorsen offered to continue his work for free. Nevertheless. Brorsen remained in Senftenberg for another 12 years, and continued his observations with his own instruments.
In 1870, he returned to his home town of Nordborg in South Jutland, which had become Prussian since the Second War of Schleswig in 1864, and subsequently was German from 1871 up to the plebiscite of 1920. In 1874, Brorsen moved into the house Løjtertoft 11, where he lived until his death. His unmarried half sister, Amalie Petrine Brorsen (1832-1911), kept the house for him. In his years in Nordborg, however, Brorsen hardly occupied himself with astronomy any more. His main interests were meteorology (also observations of the Northern Lights), as well as botany, especially orchid breeding.
Personally, Brorsen was an introverted character with relationship anxieties. He twice broke off an engagement in the last moment (first one to Louise Lassen from Sønderborg, then another one to Miss Bernkopf from Žamberk) and hence remained unmarried. Besides, there are testimonies that Brorsen developed self-willed habits in the last 25 years of his life spent in Nordborg. He did not take much care for his clothing, he let his hair grow long, and when his boots pressed his feet, he cut holes into his boots in the tight places. He used to take a daily bath in the Oldenor, a lake in Nordborg; in winter, he hoed a hole into the ice for that purpose. Brorsen died at 75 years of age, and was buried on 5 April 1895 in the cemetery of Nordborg where his grave is still preserved today.
