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 economically important estates, such as the castles of Hammershus or Helsingborg. But Tycho was reluctant to take up a position as a lord of the realm, preferring to focus on his science. He wrote to his friend Johannes Pratensis, "I did not want to take possession of any of the castles our benevolent king so graciously offered me. I am displeased with society here, customary forms and the whole rubbish". Tycho secretly began to plan to move to Basel, wishing to participate in the burgeoning academic and scientific life there. But the King heard of Tycho's plans, and desiring to