astrolabe


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astrolabe

(ăs`trəlāb), instrument probably used originally for measuring the altitudes of heavenly bodies and for determining their positions and movements. Although its origin is ancient and obscure, its invention is frequently ascribed either to Hipparchus or to Apollonius of Perga. For many centuries it was used by both astronomers and navigators. A simple astrolabe consisted of a disk of wood or metal with the circumference marked off in degrees. It was suspended by an attached ring. Pivoted at the center of the disk was a movable pointer called by Arab astronomers the alidade. By sighting with the alidade and taking readings of its position on the graduated circle, angular distances could be determined. Mariners, if sufficiently skilled in navigation, could use the astrolabe to determine latitude, longitude, and time of day and as an aid in making other calculations. It was much used on voyages of discovery in the 15th cent. and was important until the invention of the sextant in the 18th cent. The more elaborate astrolabes bore a star map (the planisphere, a circular map, was added by Hipparchus), a zodiacal circle, and various other useful or decorative devices.

astrolabe

(ass -trŏ-layb) An instrument, dating back to antiquity, used to measure the altitude of a celestial body and to solve problems of spherical astronomy. From the 15th century it was employed by mariners to determine latitude, until replaced by the sextant. There have been various types of astrolabes. One simple form consisted of a graduated disk that could be suspended by a ring to hang in a vertical plane. A movable sighting device – the alidade – pivoted at the center of the disk. Modern versions are still used to determine stellar positions and hence local time and latitude. See also prismatic astrolabe.

Astrolabe

(religion, spiritualism, and occult)

An astrolabe is a mechanical device that, prior to the development of the sextant, was widely used by mariners. Said to have been developed by Hipparchus, greatest of the ancient Greek astronomers (although some scholars give Ptolemy the honor), the astrolabe was used by astrologers when they erected horoscopes to determine the positions of the planets. (Prior to the development of ephemerides, it was necessary to actually look at the heavens when casting a horoscope.). The term astrolabe means “taking the star” in Greek, so it could be used to refer to any instrument for observing the stellar dome. Thus, in the early medieval period, astrolabe was often applied to the armillary sphere, a different instrument. The device now called an astrolabe is more properly termed a planispheric astrolabe. Originally Greek, this instrument was lost to western Europe until its reintroduction by Arabic sources.

Sources:

DeVore, Nicholas. Encyclopedia of Astrology. New York: Philosophical Library, 1947.
Tester, Jim. A History of Western Astrology. New York: Ballantine, 1987.

Astrolabe

 

a bay on the northeast coast of New Guinea (Maclay Coast). The bay is about 37 km long and 34 km wide, with depths of 40–106 m. The coast is hilly and covered with tropical vegetation. Many points on the coast have Russian names—for example, Konstantin Harbor, Cape Novosil’skii, Cape Koptev, and the Gogol River—as a result of the work done by the Russian traveler N. N. Miklukho-Maklai in New Guinea.

astrolabe

[′as·trə‚lāb]
(engineering)
An instrument designed to observe the positions and measure the altitudes of celestial bodies.

astrolabe

an instrument used by early astronomers to measure the altitude of stars and planets and also as a navigational aid. It consists of a graduated circular disc with a movable sighting device
References in periodicals archive ?
In October 2008 a small late-18th-century Persian astrolabe sold for $200,000 at Sotheby's, New York--four times its estimate (Fig.
Astrolabes at Greenwich; a catalogue of the astrolabes in the National Maritime Museum, Greenwich.
The field TEXT contains the information about where the form belongs: "Med" is Old medycynes, "Astr" is Chaucer's Astrolabe and "Equa" stands for The equatorie of the planetis.
One measuring device, the astrolabe, had two parts.
In the present four-part volume, Kari Anne Rand Schmidt addresses the question: part I surveys previous literature on the subject; part II presents the results of her computer-aided statistical analyses of the style of the Equatorie compared with the styles of three other Middle English astronomical prose works; part III contains a new facsimile of the manuscript, with facing-page transcription, and transcriptions of her control texts (Chaucer's Astrolabe, and the anonymous The Shippe of Venyse and The Newe Theorik of Planetis); and part IV a KWIC-Concordance to the text of the Equatorie.
There is a kind of aged astrolabe which someone has placed on the floor -- wherever that is.
The Rena ran aground on Astrolabe Reef 14 miles off Tauranga on the North Island on October 5.
The Liberian 'Rena' hit the Astrolabe Reef about 14 miles from Tauranga Harbour early Wednesday and has been foundering there since.
The Astrolabe tracks constellations, the planets, world time and ship time.
Did you know that the oldest known English technical manual was written in 1391 about how to use and take care of an astrolabe, an early version of a sailor's sextant (navigating instrument)?