Plane astrolabe

An astrolabe (Greek: ἀστρολάβος astrolabos; Arabic: ٱلأَسْطُرلاب‎‎ al-Asturlāb) is an elaborate inclinometer, historically used by astronomers and navigators to measure the inclined position in the sky of a celestial body, day or night. It can thus be used to identify stars or planets, to determine local latitude given local time (and vice versa), to survey, or to triangulate. It was used in classical antiquity, the Islamic Golden Age, the European Middle Ages, and the Renaissance for all these purposes.

The astrolabe is effective for determining latitude on land or calm seas, although it is less reliable on the heaving deck of a ship in rough seas. The mariner's astrolabe was developed to solve that problem.

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 Arabic word "al-Asturlāb" (i.e. astrolabe) was given various etymologies. In Arabic texts, the word is translated as "ākhdhu al-Nujuum" (Arabic: آخِذُ ٱلنُّجُومْ‎‎, lit. "star-taker"), a direct translation of the Greek word.

Al-Biruni quotes and criticizes medieval scientist Hamzah al-Isfahani who stated: "asturlab is an arabization of this Persian phrase" (sitara yab, meaning "taker of the stars"). In medieval Islamic sources, there is also a folk etymology of the word as "lines of lab", where "Lab" refers to a certain son of Idris (Enoch). This etymology is mentioned by a 10th-century scientist named al-Qummi but rejected by al-Khwarizmi.

...
Wikipedia