Astrolabe, << AS truh layb, >> is an instrument used by early astronomers and navigators to measure the angles of celestial bodies above the horizon. It consists of a metal disk mounted on a circular frame. The astrolabe is suspended so that it remains vertical. The disk has sights for observing a star, and the frame has a set of marks for measuring the star’s elevation. The astrolabe was replaced by the sextant and other more accurate instruments.
