Astrolabe
An astrolabe (Greek: ἀστρολάβος astrolabos, "star-taker") is an elaborate inclinometer, historically 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, and triangulation. It was used in classical antiquity, the Islamic Golden Age, the European Middle Ages and Renaissance for all these purposes. In the Islamic world, it was also used to calculate the Qibla and to find the times for Salat, prayers.
There is often confusion between the astrolabe and the mariner's astrolabe. While the astrolabe could be useful for determining latitude on land, it was an awkward instrument for use on the heaving deck of a ship or in wind. The mariner's astrolabe was developed to solve these problems.
Etymology
OED gives the translation "star-taker" for the English word "astrolabe" and traces it, through medieval Latin, to the Greek word astrolabos from astron "star" and lambanein "to take". In the medieval Islamic world the word "asturlab" (i.e. astrolabe) was given various etymologies. In Arabic texts, the word is translated as "akhdh al-kawakib" (lit. "taking the planets") which corresponds to an interpretation of the Greek word.Al-Biruni quotes and criticizes the medieval scientist Hamzah al-Isfahani who had stated: "asturlab is an arabization of this Persian phrase" (sitara yab, meaning "taker of the stars"). In medieval Islamic sources, there is also a "fictional" and popular etymology of the words as "lines of lab". In this popular etymology, "Lab" is a certain son of Idris (=Enoch). This etymology is mentioned by a 10th-century scientist called al-Qummi but rejected by al-Khwarizmi. "Lab" in Arabic also means "sun" and "black stony places" (cf. Dictionary).