Armillary spheres date back to the ancients, and were certainly used by the 2nd-century astronomer and mathematician Claudius Ptolemy of Alexandria. They were mathematical instruments designed to demonstrate the movement of the celestial sphere about a stationary Earth at its center.
The sphere is a skeleton celestial globe, with circles divided into degrees for angular measurement and representing the great circles of the heavens, including in the most elaborate instruments the horizon, meridian, Equator, tropics, polar circles, and an ecliptic hoop.

Each of the signs of the zodiac is engraved upon the ecliptic ring which is also calibrated with a calendar scale enabling the instrument to be used to model the apparent motion of the sun and the stars at any time of the year. The instrument could be used not only to model the movements and relative geometry of the heavens, but to carry out all sorts of calculations such as the times of sunrise and sunset, the length of a day, and the altitude of the sun or stars.
The celestial Sphere Which Rotating about it
And acts a reference system for locating the celestial bodies.

Finish : Antique Finish
Dimensions : Height 5 inch
Width : 3.5 inch
Weight : 300 grams Approx.
Base. : wood