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
Gellio Sasceride erat splendidum" ("[my] debut was excellent"). In 1590, Sasceride had sent to Galileo the only copy of a book until then found in Italy detailing the heliocentric system. The crater Sasserides on the Moon is named after him. It lies near Tycho, named after Tycho Brahe. Gellio Sasceride Gellio Sasceride (Sasserides) (1562–1612) was a Danish astronomer and medical doctor. Sasceride was born in Copenhagen. He worked as an assistant to Tycho Brahe after studying under him. It is believed that the following words were written by Sasceride to Brahe: "Quia adhuc aliquid superest spatii, quae sequuntur paucula, sic expetente typographo,