Sophia frequently visited Uranienborg, Tycho's observatory on the then-Danish island of Hveen.There, she assisted him with astronomical observations associated with his publication "De nova stella," or "On the New Star". Specifically, she assisted with a set of observations on 11 November 1572, which led to the discovery of the supernova that is now called SN 1572, as well as observations of the 8 December 1573 lunar eclipse. The discovery of SN 1572 was especially significant in that it added to the growing body of evidence that seemed to refute the geocentric model of the universe. Sophia's assistance was also instrumental in Tycho's work on orbits, which was foundational to the modern methods used to predict the positions of the planets. Tycho's studies of orbits involved the most precise measurements of the planets' movements made prior to the invention of the telescope, and while Tycho created many of the astronomical devices used to conduct the measurements, Sophia was among the assistants who actually made the measurements. Tycho did have other assistants, however, and while Sophia was present for each of these discoveries, the extent to which she contributed personally is unknown. Tycho did commend Sophia for her efforts, though, referring with admiration to Sophia's "animus invictus", or "determined mind."