An armillary sphere is an ancient astronomical instrument used to demonstrate the movements of celestial bodies...
The armillary sphere is an ancient astronomical instrument, that was used in China and Greece several centuries before our era to demonstrate various movements in the heaves. It consists of several rings that form the celestial sphere. The globe, with an observer on it, is placed in the center of the sphere. The most important great circles on this sphere are the meridian, horizon, celestial equator, and ecliptic. These circles also form the skeleton of the armillary sphere. For the armillary globe to demonstrate the celestial movements with sufficient accuracy, it must be possible to adjust it according to the geographical location of the observer. When using an armillary sphere in a room or garden for decorative purposes only, its accuracy is not so important, but they still give you a good idea of the most important features of the celestial sphere.
The armillary sphere is usually placed in a frame at an angle equal to the geographic latitude coordinate of the observer. The part of the celestial sphere that remains above the horizon is currently visible to the observer. The larger circle that passes through the poles and within which the sphere rotates, is called the celestial meridian. The wider ring represents the apparent path of the Sun as it moves through the constellations of the zodiac and is called the ecliptic ring. The smaller rings are the arctic ring in the north and the antarctic ring near the south pole. The narrow rings with which the ecliptic ring intersects, are the equatorial ring, tropic of Cancer, and tropic of Capricorn.