An Astrolabe is a historical astronomical instrument used by astronomers, navigators, and astrologers. Its many uses include locating and predicting the positions of the Sun, Moon, planets, and stars; determining local time given local latitude and vice-versa; surveying; triangulation; and to cast horoscopes. They were used in Classical Antiquity and through the Islamic Golden Age and the European Middle Ages and Renaissance for all these purposes. In the Islamic world, they were also used to calculate the Qibla and to find the times for Salah, prayers. Here is a video demonstration of an ancient Astrolabe by Tom Wujec.