A 16th-century astrolabe showing a tulip rete and.An astrolabe (: ἀστρολάβος astrolabos;: ٱلأَسْطُرلاب al-Asturlāb;: اِستاره یاب Astaara yab) is an elaborate, historically used by and to measure the above the horizon of a, day or night. It can be used to identify stars or planets, to determine local latitude given local time (and vice versa), to survey, or to. It was used in, the, the European and the for all these purposes.The astrolabe's importance not only comes from the early development of, but is also effective for determining latitude on land or calm seas.
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Although it is less reliable on the heaving deck of a ship in rough seas, the was developed to solve that problem. Contents.Etymology gives the translation 'star-taker' for the English word astrolabe and traces it through medieval Latin to the word astrolabos, from astron 'star' and lambanein 'to take'.
In the medieval Islamic world the word al-Asturlāb (i.e. Astrolabe) was given various etymologies. In Arabic texts, the word is translated as ākhidhu al-Nujūm (: آخِذُ ٱلنُّجُومْ, lit. 'star-taker'), a direct translation of the Greek word.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 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 but rejected. History Ancient world An early astrolabe was invented in the by between 220 and 150 BC, often attributed to.
The astrolabe was a marriage of the and, effectively an analog calculator capable of working out several different kinds of problems in astronomy. 405) wrote a detailed treatise on the astrolabe, and Lewis argues that used an astrolabe to make the astronomical observations recorded in the. The invention of the plane astrolabe is sometimes wrongly attributed to Theon's daughter ( c. 350–370; died 415 AD), but it is, in fact, known to have already been in use at least 500 years before Hypatia was born. The misattribution comes from a misinterpretation of a statement in a letter written by Hypatia's pupil ( c. 414), which mentions that Hypatia had taught him how to construct a plane astrolabe, but does not state anything about her having invented it herself.Astrolabes continued in use in the Greek-speaking world throughout the period. About 550 AD, Christian philosopher wrote a treatise on the astrolabe in Greek, which is the earliest extant treatise on the instrument.
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Mesopotamian bishop also wrote a treatise on the astrolabe in the in the mid-7th century. Sebokht refers to the astrolabe as being made of brass in the introduction of his treatise, indicating that metal astrolabes were known in the Christian East well before they were developed in the Islamic world or in the Latin West. Medieval era. Animation showing how and are mapped on an astrolabe's tympan through a. Hypothetical tympan of a 16th-century European astrolabe.Astrolabes were further developed in the, where introduced angular scales to the design, adding circles indicating on the.
It was widely used throughout the Muslim world, chiefly as an and as a way of finding the, the direction of. Eighth-century is the first person credited with building the astrolabe in the Islamic world.The mathematical background was established by Muslim astronomer in his treatise Kitab az-Zij (c. 920 AD), which was translated into Latin by ( De Motu Stellarum).
The earliest surviving astrolabe is dated 315 (927–28 AD). In the Islamic world, astrolabes were used to find the times of sunrise and the rising of fixed stars, to help schedule morning prayers. In the 10th century, first described over 1,000 different uses of an astrolabe, in areas as diverse as, timekeeping, prayer, etc. Observing the with an Astrolabium, by., Belgium.Mechanical were initially influenced by the astrolabe; they could be seen in many ways as clockwork astrolabes designed to produce a continual display of the current position of the sun, stars, and planets. For example, 's clock (c. 1330) consisted essentially of a star map rotating behind a fixed rete, similar to that of an astrolabe.Many astronomical clocks use an astrolabe-style display, such as the famous, adopting a stereographic projection (see below) of the ecliptic plane.
In recent times, astrolabe watches have become popular. For example, Swiss watchmaker designed and built an astrolabe wristwatch in conjunction with in 1985. Dutch watchmaker Christaan van der Klauuw also manufactures astrolabe watches today. Construction. Computer-generated planispheric astrolabeAn astrolabe consists of a disk, called the mater (mother), which is deep enough to hold one or more flat plates called tympans,. A is made for a specific and is engraved with a of denoting and and representing the portion of the above the local horizon. The rim of the mater is typically graduated into, or both.Above the mater and tympan, the rete, a framework bearing a projection of the plane and several indicating the positions of the brightest, is free to rotate.
These pointers are often just simple points, but depending on the skill of the craftsman can be very elaborate and artistic. There are examples of astrolabes with artistic pointers in the shape of balls, stars, snakes, hands, dogs' heads, and leaves, among others. The names of the indicated stars were often engraved on the pointers in Arabic or Latin.
Some astrolabes have a narrow or label which rotates over the rete, and may be marked with a scale of.The rete, representing the, functions as a. When it is rotated, the stars and the move over the projection of the coordinates on the tympan.
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One complete rotation corresponds to the passage of a day. The astrolabe is, therefore, a predecessor of the modern.On the back of the mater, there is often engraved a number of scales that are useful in the astrolabe's various applications. These vary from designer to designer, but might include curves for time conversions, a for converting the day of the month to the sun's position on the ecliptic, trigonometric scales, and graduation of 360 degrees around the back edge. The is attached to the back face. An alidade can be seen in the lower right illustration of the Persian astrolabe above.
When the astrolabe is held vertically, the alidade can be rotated and the sun or a star sighted along its length, so that its altitude in degrees can be read ('taken') from the graduated edge of the astrolabe; hence the word's Greek roots: 'astron' (ἄστρον) = star + 'lab-' (λαβ-) = to take.See also., designer and maker of, globes and astrolabes.References Footnotes.