La Petite Ourse appelée vulgairement la Petite Casserole et l’Etoile Polaire (83°N 20°W). © UNIL

La jambe, le nombril et l’épaule du Pégase (20°N 27°W). © UNIL

Gerardus Mercator tried to improve his terrestrial globe by adding stars (as Gemma Frisius did) that could serve as reference points for travellers. The terrestrial globe shows 29 stars in several different areas: in the seas, in the middle of the deserts of Africa, on the plains of America and Asia and near the North Pole. Their size and brightness were meant to help travellers get their bearings.

Mercator may have wanted to help sailors or travellers to find their way more easily during the night, an aim that the compass set into the horizon ring also suggests. These features thus combined the terrestrial and celestial globes in one, supposedly making it less cumbersome than taking both on a journey. It seems unlikely, however, that even the terrestrial globe alone would have been a travelling companion.