Astrolabe, historical artwork. An astrolabe was a historical astronomical device used to predict the positions of the stars and other astronomical bodies. It can also be used to determine local time from local latitude and vice-versa, as well as being used for surveying and triangulation. They were used for astrology, astronomy and navigation. The outer edge of the base material (which can be rotated with respect to the overlying markers) is marked in both degrees and the 24-hour division of the day. The inner circle is marked with the signs of the zodiac, while the other markers show other constellations. The angled pointers are used to measure angles of inclination for astronomical bodies.