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Topic: Astrolabe


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In the News (Sun 21 Apr 19)

  
 An Astrolabe date 1559
An astrolabe is a two dimensional representation of the Ptolemaic cosmos, with the earth at its centre, showing the movement of the celestial sphere around the pole and allowing the relative position of stars to be determined at any given moment for one particular latitude.
Astrolabes could also be used for time-telling, by day or by night, as long as the sun or some recognisable star present on the rete was visible.
In this type of universal or ‘catholic’ projection the centre of the astrolabe and the projection correspond to the spring equinox, which is represented spatially as the point of intersection of the celestial equator and the ecliptic.
www.antiquorum.com /html/vox/vox2003/astrolabe/astrolabe.htm   (1977 words)

  
 Astrolabe - Wikipedia, the free encyclopedia
No one knows for certain who invented the astrolabe, but it was the chief navigational instrument until the invention of the sextant in the 16th century.
Brass astrolabes were developed in much of the Islamic world, chiefly as an aid to finding the qibla.
Some astrolabes have a narrow rule which rotates over the rete, and may be marked with a scale of declinations.
en.wikipedia.org /wiki/Astrolabe   (650 words)

  
 ESI_RepInstIndex
Astrolabes are probably the the sini qua non of ancient instruments.
The Astrolabe site on the Internet provides a brief essay on the astrolabe, museums having astrolabe collections, a history of the astrolabe, and finally, astrolabe links, references, and reproductions, including a "personal astrolabe" available for a fee made by that site's creator.
Mariner's Astrolabe: the classic form of the navigator's astrolabe as used by the Portuguese and the Spanish in the 16th and 17th century.
www.humboldt.edu /~rap1/EarlySciInstSite/Instruments/RepInst.htm   (799 words)

  
 [No title]   (Site not responding. Last check: 2007-11-05)
The astrolabe is a very ancient astronomical computer for solving problems relating to time and the position of the Sun and stars in the sky.
The principles of the astrolabe projection were known before 150 B.C., and true astrolabes were made before A.D. The astrolabe was highly developed in the Islamic world by 800 and was introduced to Europe from Islamic Spain (Andalusia) in the early 12th century.
Astrolabes are still appreciated for their unique capabilites and their value for astronomy education.
www.uniquecanes.com /Astrolabe.html   (373 words)

  
 The Astrolabe   (Site not responding. Last check: 2007-11-05)
The Astrolabe is an instrument --- part observing tool and part calculator --- used from ancient times up until the 17th century, when the invention of the telescope displaced it as the premier tool of astronomers.
The astrolabe is, in essence, a two-dimensional model of the celestial sphere in relation to the earth, based on the assumption that the earth is in the centre of the universe.
Additionally on the back of an astrolabe there can be further calendrical information such as the solar cycle, tables for the determination of the date of Easter, saints' names together with the calendrical scales (the choice of the saints' names sometimes allow the determination of the provenance of an instrument), astrological tables and so on.
www.cas.muohio.edu /~devriepl/phy211/astrolabe/MyNotes1.htm   (1524 words)

  
 Astrolabe - Parts
Later, when the various uses of the astrolabe are discussed, I have included the definitions of some of the more esoteric terms as JavaScript links.
The rule is simply the pointer on the face of the astrolabe that is used to find the result of whatever you are calculating and is held in place with the pin.
During the day, when sighting the sun, the astrolabe is held chest height and looking at the shadow cast on your chest.
members.cox.net /hapnueby/astrolabe/parts.html   (1910 words)

  
 The Astrolabe
Typical uses of the astrolabe include finding the time during the day or night, finding the time of a celestial event such as sunrise or sunset and as a handy reference of celestial positions.
The typical astrolabe was not a navigational instrument although an instrument called the mariner's astrolabe was widely used.
The largest astrolabe collection in North America, and the best displayed in the world, is at the Adler Planetarium and Astronomy Museum in Chicago, IL.
www.astrolabes.org   (931 words)

  
 Mariner's Astrolabe - Mel Fisher Maritime Heritage Society and Museum in Key West, Florida
The mariner’s astrolabe was derived from the more complex, planispheric astrolabe which was used by early astronomers to calculate the movements of the heavens.
Suspending the astrolabe by the second finger of the right hand, the observer determined the direction of the sun by noting the angle of the shadows, and then faced it directly.
The astrolabe was held side-on to the sun and the alidade rotated until the light rays passed through both pinnules.
www.melfisher.org /astrolabe.htm   (1106 words)

  
 07 Making a Simple Astrolabe - At Home Astronomy   (Site not responding. Last check: 2007-11-05)
An astrolabe (pronounced AS'-tro-layb) is a device used for measuring altitude, including the height of objects in the sky.
Used to determine the latitude of a ship at sea by measuring the altitude of the Sun or star, the mariner's Astrolabe was popular in the late 15th and early 16th Centuries.
Carefully poke a small hole through the astrolabe where the "X" is marked, pass the string through it, and either knot the string at the back of the cardboard or tape it there.
cse.ssl.berkeley.edu /AtHomeAstronomy/activity_07.html   (388 words)

  
 Encyclopedia: Astrolabe   (Site not responding. Last check: 2007-11-05)
A Treatise on the Astrolabe is a medieval essay on the astrolabe by Chaucer.
The Astrolabe material is Pewter, and is available in a pewter finish or in the gold plate.
Afternoon Then he takes out the Rules for the Astrolabe and using the constellation in which the stars were located that morning (across the top of the table), and the number of degrees that the sun was above the horizon at midday, he looks up the latitude.
www.nationmaster.com /encyclopedia/Astrolabe   (2031 words)

  
 Astrolabe
The astrolabe is a device for solving problems relating to time and the position of the Sun and stars in the sky.
A stereographic projection is used for the mapping of the celestial sphere on the astrolabe plane (a so called conformal -angle preserving – projection, that maps circles to circles).
The Astrolabe was mainly developed in the Islamic world after the translation of Greek manuscripts around 800 AD in a period of ca.
www.mlahanas.de /Greeks/Astrolabe.htm   (853 words)

  
 The ASTROLABE, by Gary Agranat and Dave Delligati, Fall 1980   (Site not responding. Last check: 2007-11-05)
By the thirteenth century the astrolabe was known and used from India in the east, to Spain in the west, and from the tropics to Britain and Scandanavia.
The stimulation for the astrolabe and astronomy in Islam was a great religious enthusiasm--an enthusiasm that gave rise to trades and crafts under social and economic prosperity, creating a thriving civilization.
The importance of the astrolabe in Islam that influences us today is that it helped preserve Greek astronomy and was a source of stimulation for the astronomers and instrument makers of the Middle Ages in Europe.
members.aol.com /chopstcks/gca7sky/astrolabe.htm   (2405 words)

  
 astrolabe Montgomery College's Planetarium   (Site not responding. Last check: 2007-11-05)
The astrolabe was the most important astronomical calculating device before the invention of digital computers and was the most important astronomical observational device before the invention of the telescope.
If you want to hold in your hand a model of the universe, an astrolabe, which is undoubtedly the best astrolabe made in the last 400 years and a peer to the best ancient instruments, in some ways their superior, contact:
Besides the astrolabe a 40 plus page booklet is included telling how to use the astrolabe and some of it fascinating history.
www.mc.cc.md.us /Departments/planet/planet/Astrolab.htm   (484 words)

  
 The Columbia Encyclopedia, Sixth Edition: astrolabe @ HighBeam Research   (Site not responding. Last check: 2007-11-05)
ASTROLABE [astrolabe], instrument probably used originally for measuring the altitudes of heavenly bodies and for determining their positions and movements.
A simple astrolabe consisted of a disk of wood or metal with the circumference marked off in degrees.
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.
www.highbeam.com /library/doc0.asp?DOCID=1E1:astrolab&refid=ip_encyclopedia_hf   (243 words)

  
 Astrolabe History
An astrolabe is a two-dimensional model of the celestial sphere.
One of the best descriptions of the astrolabe and its use was written in 1392 by Geoffrey Chaucer, in England; the TOPS astrolabe is inspired from that text.
The most important part of the traditional astrolabe is a circular plate of metal, usually about 6 inches in diameter, which could be suspended by a ring from which it would hang perfectly vertical.
www.ifa.hawaii.edu /tops/astl-hist.html   (520 words)

  
 The Astrolabe
Arabic craftsmen (9th-11th centuries) improved the astrolabe to determine time from stellar or solar observations without use of tables, though it was limited to one century and one latitude.
English poet Geoffrey Chaucer describes an astrolabe in detail in his Treatise on the Astrolabe (1381).
The Astrolabe is useful in determining the altitude of objects in the sky.
www.physics.sfasu.edu /markworth/astrolabe.htm   (494 words)

  
 An Introduction to a Treatise on the Astrolabe
The use of the Astrolabe was no doubt well known at an early period in India and among the Persians and Arabs; see the `Description of a Planispheric Astrolabe constructed for Sháh Sultán Husain Safawí, King of Persia,' by W. Morley, in which elaborate and beautifully illustrated volume the reader may find sufficient information.
The most important part of the `astrolabe planisphere' consisted of a somewhat heavy circular plate of metal from four to seven inches in diameter, which could be suspended from the thumb by a ring (i.
The astrolabe can be used to find the degree of the zodiac with which any planet ascends, even when the planet is not situated in the ecliptic (ii.
users.rcn.com /detroyes/astrolabe/intro.html   (6872 words)

  
 Civilization.ca - Treasures Gallery - Champlain's astrolabe
The astrolabe was willed to the New York Historical Society in 1942 where it remained until June 1989, when it was acquired by the Department of Communications for the Canadian Museum of Civilization.
It is the smallest of 35 mariner's astrolabes surviving from the early part of the seventeenth century and the only one from France.
The ring was probably broken off sometime in the late nineteenth century, since it appears in an 1879 photograph of the astrolabe.
www.civilization.ca /tresors/treasure/222eng.html   (307 words)

  
 The Astrolabe by Norman Greene, the Astrolabe Maker   (Site not responding. Last check: 2007-11-05)
The time of day or night is on the outside edge with noon at the top of the Astrolabe and midnight at the bottom.
The Astrolabe was developed at the Greek school in Alexandria about 160 B.C. by Hipparchus.
The Astrolabe was known to scholars from then on, and was used as a slide rule of the Heavens.
www.puzzlering.net /astrolabe.html   (493 words)

  
 Treatise on the Astrolabe - Wikipedia, the free encyclopedia
A Treatise on the Astrolabe is a medieval essay on the astrolabe by Geoffrey Chaucer.
Little Lewis my son, certain evidence enables me to well perceive your ability to learn the sciences, including numbers and proportions; and I have also heard your constant requests to learn of the astrolabe in particular.
The Treatise is considered the oldest work in English describing a complex scientific instrument, and is admired for its clarity in explaining difficult concepts -- although since the astrolabe and related tools are no longer in common use, much of it is difficult for modern readers to understand.
en.wikipedia.org /wiki/Treatise_on_the_Astrolabe   (274 words)

  
 The Islamic Astrolabe   (Site not responding. Last check: 2007-11-05)
The earliest surviving Arabic astrolabe treatises are from the seventh and eighth centuries and are often translations of earlier Greek or Syriac texts.
These simplified the process of astrolabe construction by removing the need for mathematical calculation of these values, indicating that astrolabes were being manufactured in substantial numbers since the effort involved in producing the tables would have been considerable.
On the back is a shadow square for measuring the heights of inaccessible things and other similar calculations (shadow squares are quite common, but not on all astrolabes), and scales for calendrical calculations and calculation of the qibla (the direction to face during prayers).
www.hps.cam.ac.uk /starry/isaslabe.html   (465 words)

  
 Astrolabe
An astrolabe is an instrument for telling time by sighting the Sun or another known star.
The astrolabe is a delightful, surprisingly precise instrument -- provides the time to within a few minutes, except near noon.
The astrolabe had to be designed for a specific location and year.
www.rism.com /Trig/astrolabe.htm   (3347 words)

  
 The History of the Sextant   (Site not responding. Last check: 2007-11-05)
Mariner's astrolabes are now very rare and expensive - less than one hundred are known to survive and most of these are in poor condition having been recovered from ship wrecks.
Astrolabe in use.For a sun sight, the astrolabe was allowed to hang freely and the alidade was adjusted so that a ray of sunlight passed through the hole in the upper vane and fell precisely on the hole in the lower vane.
The astrolabe was popular for more than 200 years because it was reliable and easy to use under the frequently adverse conditions aboard ship.
www.mat.uc.pt /~helios/Mestre/Novemb00/H61iflan.htm   (2901 words)

  
 Celestaire, Inc.: Planispheric Astrolabe
The Astrolabe is one of the earliest, and at the same time, one of the most sophisticated of all ancient scientific instruments.
Although designed in the manner of the beautiful Renaissance instruments, this is an original Astrolabe, computed for modern star positions, useful through the year 2046.
Through the high quality materials, and ease of assembly, one not only creates a working instrument, but is afforded a wonderful opportunity to study and relate to historical navigational methods.
www.celestaire.com /catalog/products/1701.html   (136 words)

  
 Celestaire, Inc.: Mariner's Astrolabe   (Site not responding. Last check: 2007-11-05)
This astrolabe was developed by the Portuguese in the 15th Century (much later than the "planispheric" astrolabe).
It was designed to be used for both sun and star observations, and as a practical working model is the simplest of all to use.
The construction of this astrolabe kit, is precision die-cut in metallic surfaced cardboard.
www.celestaire.com /catalog/products/1703.html   (71 words)

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