Tycho Brahe produce much of his astronomical data, Tycho relied heavily on the then new technique of "prosthaphaeresis", an algorithm for approximating products based on trigonometric identities that predated logarithms. Although Tycho admired Copernicus and was the first to teach his theory in Denmark, he was unable to reconcile Copernican theory with the basic laws of Aristotelian physics, that he considered to be foundational. He was also critical of the observational data that Copernicus built his theory on, which he correctly considered to have a high margin of error. Instead, Tycho proposed a "geo-heliocentric" system in which the Sun and Moon orbited
Tycho Brahe in 1580, taught Count Wilhelm of Kassel and his astronomer Christoph Rothmann to build copies of Brahe's instruments without permission from Brahe. In turn, Craig, who had studied with Wittich, accused Brahe of minimizing Wittich's role in developing some of the trigonometric methods used by Brahe. In his dealings with these disputes, Tycho Brahe made sure to leverage his support in the scientific community, by publishing and disseminating his own answers and arguments. When Frederick died in 1588, his son and heir Christian IV was only 11 years old. A regency council was appointed to rule for the young prince-elect