If the five-year delay imposed by the initial requirements of getting established on Hven had gotten Tycho off to a slow start in his work, that situation was only a memory by 1590. By this time, Tycho was well under way in his long-envisioned renovation of the whole science of astronomy. Already in 1588 he mentioned plans for presenting it in the form of a mighty Opus astronomicum, a sort of “New Almagest” that would begin with a discussion of his instruments and proceed from there in much the same way that Ptolemy and Copernicus had done. Even then, Tycho recognized that he was still a long time – five or six years, at least – from this achievement, because he still lacked some of the requisite observations for the slower moving (superior) planets.

Each year, however, there was more competition for his research time, generally from projects he had not originally conceived as part of his “redintegration.” Of longest standing was his cosmological trilogy on the “more recent celestial phenomena,” designed to prove that the prevailing Aristotelian view of the world was simply untenable, that there were no comets below the moon, no solid spheres above the moon, and, by implication, no reason to adhere to any other aspect of traditional, largely a priori, dogma.

At the beginning of 1590, Tycho was still heavily mired in this undertaking. Volume II (De mundi) had been printed and was in the hands of various friends, dignitaries, and acquaintances.