what is an armillary sphere
1 The armillary sphere is also called as spherical astrolabe, armilla and armil. 2  Armillary sphere is a learning tool used for determining the position of the Sun and stars and used by sailors for navigating. 3  It was used in Greece and throughout Asia and the Islamic Empire. The outer rings represent the principal circles of heaven. 2  At first the sphere was set to a suitable latitude by confirming the outer meridian ring was vertical to the horizon and horizontal to actual meridian. 3  Position of armillary sphere was started by spotting on a celestial object such as sun or star.