armillary sphere 
noun
A model of the celestial globe constructed from rings and hoops representing the equator, the tropics, and other celestial circles, and able to revolve on its axis.The clock is a tower topped by an armillary sphere and celestial globe of mechanical and hydraulic engineering, about thirty-five feet high....
- But, by means of suitable constructions within the armillary sphere, they were able to reduce many of their problems to comparison of similar right-angled plane triangles.
- Zhang appears to have been the first person in China to construct an equatorial armillary sphere.
Origin
Mid 17th century: from modern Latin armillaris 'relating to an armilla', an astronomical instrument consisting of a hoop fixed in the plane of the equator (sometimes crossed by one in the plane of the meridian), used by the ancient astronomers to show the recurrence of equinoxes and solstices; from Latin armilla 'bracelet'.