From the late 1620s onwards, Jesuit astronomers got increasingly involved in the physical discussion of the structure and composition of the cosmos. They accordingly made recourse to Tychonic ideas on topics such as celestial matter and fluidity. Nevertheless, they still explicitly avoided crediting Tycho Brahe and his correspondents with these new notions. Aligned with the Catholic Church guidelines issued by the Council of Trent, Jesuits strove to credit the First Church Fathers with the source of their theories. This study demonstrates, nevertheless, that they were influenced by Tycho Brahe and Christoph Rothmann. This was part of the strategy to incorporate the Lutheran Tycho into the framework of Jesuit authorities. Thus, while Tycho Brahe entered the pantheon of ‘Jesuit’ authorities, he nonetheless was not granted the absolute status of intellectual authority.