Upon completing his studies in Kraków, Nicolaus ’ uncle ​ — who by now had become the bishop of Warmia — ​ asked him to move to Frombork, a city on the Baltic Sea.
Astoņpadsmit gadu vecumā viņš pārcēlās uz toreizējo Polijas galvaspilsētu Krakovu, kur iestājās universitātē un aizrāvās ar astronomiju.