armillary sphere
Concise Oxford English Dictionary © 2008 Oxford University Press:
armillary sphere
▶noun a revolving model of the celestial sphere constructed from metal rings representing the equator, the tropics, etc.
– origin C17: from mod. L. armillaris ‘relating to an armilla’, a similar astronomical instrument used by ancient astronomers, from L. armilla ‘bracelet’.
'armillary sphere' also found in these Oxford entries:

