In 1628, he began studying under Philippe van Lansberge, who was introduced to him by Beeckman. Van den Hove became an enthusiastic supporter of Landsberge, who was by now quite aged, and helped Landsberge complete his project to "restore astronomy". Landsberge thanked Van den Hove publicly, considered himself lucky that "by divine providence, in my old age, pressed by sickness, such a strong helper came to my aid, as formerly the learned Rheticus to the great Copernicus." In 1632, at Copenhagen and later reprinted at London in 1696, Petrus Bartholin published Apologia pro observationibus, et hypothesibus...Tycho Brahe...Contra...Martini Hortensii Delfensis criminationes et calumnies, quas in praefationem commentationum praeceptoris sui Philippi Lansbergii Middelburgensis, de motu terrae diurno et annuo etc. cosarcinnavit. Van den Hove had attacked many of Tycho Brahe's claims in his preface to his Latin translation of a work by Landsbergen. This was the Commentationes in motum terrae diurnum, & annuum. The first Latin edition of Landsberge's illustrated treatise, the Commentationes taught the probability of earth’s motion according to the Copernican theory. Van den Hove regarded Landsberge, not Tycho Brahe, as the one who was restoring astronomy. "Only Landsberge held all ancient observations in esteem," Van den Hove wrote, "whereas Tycho, Longomontanus, and Kepler tended to neglect them."
Career as lecturer
At the encouragement of Gerard Vossius and Caspar Barlaeus, Van den Hove began lecturing on the mathematical sciences at the Amsterdam Atheneum in 1634. The Athenaeum Illustre, which had its seat in the fourteenth century Agnietenkapel, is commonly regarded as the predecessor of the University of Amsterdam. Upon assuming his new duties, Van den Hove delivered an inaugural speech, later published as De dignitate et utilitate Matheseos. Van den Hove also lectured on optics at Amsterdam, and on navigation. In 1638, Van den Hove was made a member of the commission negotiating with Galileo on the determination of longitude by the method of Jupiter's moons.
Volker R. Remmert, What Do You Need a Mathematician For? Martinus Hortensius’s “Speech on the Dignity and Utility of the Mathematical Sciences” , in: The Mathematical Intelligencer 26:4, 40-47
Annette Imhausen/Volker R. Remmert: The Oration on the Dignity and the Usefulness of the Mathematical Sciences of Martinus Hortensius : Text, Translation and Commentary, in: History of Universities 21, 71-150