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 days Tycho Brahe days In the folklore of Scandinavia, Tycho Brahe days (Danish: "Tycho Brahes-dage"; Norwegian: "Tycho Brahedager"; Swedish: "Tycho Brahe-dagar") are days judged to be especially unlucky, especially for magical work, and important business transactions[ and personal events]. Tycho Brahe (1546–1601) was a Danish astronomer, astrologer, and alchemist and as such achieved some acclaim in popular folklore as a sage and magician. The idea that certain calendar dates are lucky or unlucky is of ancient origin, going back as far as the Mesopotamian civilizations. Tables that identify lucky and unlucky days are sometimes known by the German label of "Tagwählerei".