Christen Sørensen Longomontanus

Christen Sørensen Longomontanus (also as Longberg or Severin) (4 October 1562 – 8 October 1647) was a Danish astronomer. The name Longomontanus was a Latinized form of the name of the village of Lomborg, Jutland, Denmark, where he was born. His father, a laborer called Søren, or Severin, died when Christen was eight years old. An uncle took charge of the child, and had him educated at Lemvig; but after three years sent him back to his mother, who needed his help to work the fields. She agreed that he could study during the winter months with the clergyman of the parish; this arrangement continued until 1577, when the ill-will of some of his relatives and his own desire for knowledge caused him to run away to Viborg. There he attended the grammar school, working as a labourer to pay his expenses, and in 1588 went to Copenhagen with a high reputation for learning and ability. Engaged by Tycho Brahe in 1589 as his assistant in his great astronomical observatory of Uraniborg, he rendered invaluable service for eight years. He held Tycho Brahe in the highest regard and always supported his system and tried to improve upon it throughout his life. However, he did disagree with the Tycho Brahe's system in some regards, he believed that the earth rotated unlike his master's theory that it was immobile. During this time, Kepler joined the two in trying to come up with a theory on how to predict longitude at oppositions with complete accuracy. Longomontanus used Mars as a model for this. Having left the island of Hven with his master, he obtained his discharge at Copenhagen on 1 June 1597, in order to study at some German universities. He rejoined Tycho at Prague in January 1600, and having completed the Tychonic lunar theory, turned homeward again in August. Soon after this, Tycho Brahe’s untimely demise happened. After Tycho managed to become an mathematician that served the Emperor Rudolph II, he died in October 1601. The Emperor had to appoint a new Mathematician. When doing so, the expected choice would have been Longomontanus since he was Tycho’s preferred choice.