Altitude circles? for the celestial navigational globe. Astronomical details on the sphere include stars marked with star shapes, some are named but most are only represented by a Greek letter. The constellations are marked in as much as they are named, in capitals in the area on the globe in which they are found. There are no markers to show constellation boundaries, nor any lines joining stars. In all, approximately 41 constellations are named. This globe was almost certainly used as a teaching aid for navigators. For full details about the cartography and construction of this globe please contact the Royal Observatory Greenwich.