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The Great Contribution of Islamic Astronomers

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Author Topic: The Great Contribution of Islamic Astronomers  (Read 3662 times)
Bianca
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« Reply #90 on: October 13, 2008, 12:17:25 pm »



A Persian (Iranian) astrolabe from 1208.
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« Reply #91 on: October 13, 2008, 12:26:01 pm »











Large astrolabe



Ibn Yunus accurately observed more than 10,000 entries for the sun's position for many years using a large astrolabe with a diameter of nearly 1.4 meters.[35]





Mechanical geared astrolabe



The first mechanical astrolabes with gears were invented in the Muslim world, and were perfected by Ibn Samh (c. 1020). One such device with eight gear-wheels was also constructed by Abū Rayhān al-Bīrūnī in 996.

These can be considered as an ancestor of the mechanical clocks developed by later Muslim engineers.

 




Navigational astrolabe



The first navigational astrolabe was invented in the Islamic world during the Middle Ages, and employed the use of a polar projection system.






Orthographical astrolabe



Abu Rayhan al-Biruni invented and wrote the earliest treatise on the orthographical astrolabe in the 1000s.
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« Reply #92 on: October 13, 2008, 12:27:02 pm »



An 18th century Persian astrolabe,
kept at

The Whipple Museum of the History of Science in
Cambridge,
England.



http://en.wikipedia.org/wiki/Islamic_astronomy
« Last Edit: October 13, 2008, 12:31:38 pm by Bianca » Report Spam   Logged

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« Reply #93 on: October 13, 2008, 01:47:25 pm »

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« Reply #94 on: October 13, 2008, 01:53:43 pm »



An astrolabe from al-Andalus dating back to 1067.
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« Reply #95 on: October 13, 2008, 01:56:24 pm »










Saphaea and Zuraqi



The first astrolabe instruments were used to read the rise of the time of rise of the Sun and fixed stars.

In the 11th century, Arzachel (al-Zarqali) of al-Andalus constructed the first universal astrolabe which, unlike its predecessors, did not depend on the latitude of the observer, and could be used anywhere on the Earth.

This universal astrolabe instrument became known in Europe as the "Saphaea".

Another astrolabe, the Zuraqi is a unique astrolabe invented by al-Sijzi for a heliocentric planetary model in which the Earth is moving rather than the sky.






Linear astrolabe



A famous work by Sharaf al-Dīn al-Tūsī is one in which he describes the linear astrolabe, sometimes called the "staff of al-Tusi", which he invented.






Astrolabic clock



Ibn al-Shatir invented the astrolabic clock in 14th century Syria.
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« Reply #96 on: October 13, 2008, 02:01:35 pm »



PLANISPHERE
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« Reply #97 on: October 13, 2008, 02:06:24 pm »










Equatorium



The Equatorium was an analog computer invented by Abū Ishāq Ibrāhīm al-Zarqālī (Arzachel) in
al-Andalus, probably around 1015 CE.

It is a mechanical device for finding the longitudes and positions of the Moon, Sun, and planets, without calculation using a geometrical model to represent the celestial body's mean and anomalistic position.





 
The planisphere,


the earliest star chart, was invented by Abū Rayhān al-Bīrūnī.Planisphere and star chart

In the early 11th century, Abū Rayhān al-Bīrūnī invented and wrote the first treatise on the planisphere, which was the earliest star chart and an early analog computer.






Mechanical geared calendar computer



Abū Rayhān al-Bīrūnī also invented the first mechanical lunisolar calendar computer which employed a gear train and eight gear-wheels.

This was an early example of a fixed-wired knowledge processing machine.





 
The torquetum


was invented by Jabir ibn Aflah (Geber).


Jabir ibn Aflah (Geber) (c. 1100-1150) invented the torquetum, an observational instrument and mechanical analog computer device used to transform between spherical coordinate systems.

It was designed to take and convert measurements made in three sets of coordinates: horizon, equatorial, and ecliptic.
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« Reply #98 on: October 13, 2008, 02:08:07 pm »



                                    

                                    The torquetum was invented by
                                    Jabir ibn Aflah (Geber).
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« Reply #99 on: October 13, 2008, 02:14:06 pm »










Mechanical astrolabe with geared calendar computer



In 1235, Abi Bakr of Isfahan invented a brass astrolabe with a geared calendar movement based on
the design of Abū Rayhān al-Bīrūnī's mechanical calendar computer.

Abi Bakr's geared astrolabe uses a set of gear-wheels and is the oldest surviving complete mechanical geared machine in existence.






Plate of Conjunctions


 
In the 15th century, al-Kashi invented the Plate of Conjunctions, a computing instrument used
to determine the time of day at which planetary conjunctions will occur, and for performing linear interpolation.






Planetary computer



In the 15th century, al-Kashi also invented a mechanical planetary computer which he called the
Plate of Zones, which could graphically solve a number of planetary problems, including the prediction of the true positions in longitude of the Sun and Moon, and the planets in terms of elliptical orbits;
the latitudes of the Sun, Moon, and planets; and the ecliptic of the Sun.

The instrument also incorporated an alhidade and ruler.
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« Reply #100 on: October 13, 2008, 02:18:11 pm »










                                                          Astronomical clocks






The Muslims constructed a variety of highly accurate astronomical clocks for use in their observatories.




Water-powered astronomical clocks



Al-Jazari invented monumental water-powered astronomical clocks which displayed moving models of the Sun, Moon, and stars.

His largest astronomical clock displayed the zodiac and the solar and lunar orbits.

Another innovative feature of the clock was a pointer which traveled across the top of a gateway and caused automatic doors to open every hour.






Spring-powered astronomical clock



Taqi al-Din invented the first astronomical clock to be powered by springs, first described in his
'The Brightest Stars for the Construction of Mechanical Clocks' (1556-1559).






Mechanical alarm clock



Taqi al-Din invented the first mechanical alarm clock, which he described in 'The Brightest Stars for
the Construction of Mechanical Clocks' (Al-Kawākib al-durriyya fī wadh' al-bankāmat al-dawriyya) in 1559.

His alarm clock was capable of sounding at a specified time, which was achieved by means of placing
a peg on the dial wheel to when one wants the alarm heard and by producing an automated ringing device at the specified time.






Mechanical observational clock



Taqi al-Din invented the "observational clock", which he described as "a mechanical clock with three dials which show the hours, the minutes, and the seconds."

This was the first clock to measure time in seconds, and he used it for astronomical purposes, specifically for measuring the right ascension of the stars.

This is considered one of the most important innovations in 16th-century practical astronomy, as previous clocks were not accurate enough to be used for astronomical purposes.

He further improved the observational clock, as described in his Sidrat al-muntaha, using only one
dial to represent the hours, minutes and seconds. He describes this observational clock as



"a mechanical clock with a dial showing the hours, minutes and seconds and we divided every minute

into five seconds."
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« Reply #101 on: October 13, 2008, 02:19:56 pm »



A sundial in Seville,
Andalusia, Spain
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« Reply #102 on: October 13, 2008, 02:24:25 pm »










                                                           D I A L S






Muslim astronomers and engineers invented a variety of dials for timekeeping, and for determining the times of the five daily prayers.

Muslims made several important improvements to the theory and construction of sundials, which they inherited from their Indian and Hellenistic predecessors.

Al-Khwarizmi made tables for these instruments which considerably shortened the time needed to make specific calculations. Muslim sundials could also be observed from anywhere on the Earth.

Sundials were frequently placed on mosques to determine the time of prayer. One of the most striking examples was built in the 14th century by the muwaqqit (timekeeper) of the Umayyad Mosque in Damascus, Ibn al-Shatir

Muslim astronomers and engineers were the first to write instructions on the construction of horizontal sundials, vertical sundials, and polar sundials.

Since ancient dials were nodus-based with straight hour-lines, they indicated unequal hours — also called temporary hours — that varied with the seasons, since every day was divided into twelve equal segments; thus, hours were shorter in winter and longer in summer.

The idea of using hours of equal time length throughout the year was the innovation of Abu'l-Hasan Ibn al-Shatir in 1371, based on earlier developments in trigonometry by Muhammad ibn Jābir al-Harrānī al-Battānī (Albategni).

Ibn al-Shatir was aware that "using a gnomon that is parallel to the Earth's axis will produce sundials whose hour lines indicate equal hours on any day of the year." His sundial is the oldest polar-axis sundial still in existence. The concept later appeared in Western sundials from at least 1446.






Navicula de Venetiis



This was a universal horary dial invented in 9th century Baghdad.

It was used for accurate timekeeping by the Sun and Stars, and could be observed from any latitude.

This was later known in Europe as the "Navicula de Venetiis", which was considered the most sophisticated timekeeping instrument of the Renaissance.






Compass dial



In the 13th century, Ibn al-Shatir invented the compass dial, a timekeeping device incorporating
both a universal sundial and a magnetic compass. He invented it for the purpose of finding the
times of Salah prayers.
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« Reply #103 on: October 13, 2008, 02:27:26 pm »




                         

                         An armillary sphere.
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« Reply #104 on: October 13, 2008, 02:31:41 pm »








                                                                     G L O B E S





 
Armillary sphere



An armillary sphere had similar applications to a celestial globe.

No early Islamic armillary spheres survive, but several treatises on “the instrument with the rings” were written.

 







The spherical astrolabe was invented
by Islamic astronomers.



The spherical astrolabe was first produced in the Islamic world.

It was an Islamic variation of the astrolabe and the armillary sphere, of which only one complete instrument,
from the 14th century, has survived.







Terrestrial globe



The first terrestrial globe of the Old World was constructed in the Muslim world during the Middle Ages,

by Muslim geographers and astronomers working under the Abbasid caliph, Al-Ma'mun, in the 9th century.






Celestial globes



Celestial globes were used primarily for solving problems in celestial astronomy.

Today, 126 such instruments remain worldwide, the oldest from the 11th century. The altitude of the sun,
or the Right Ascension and Declination of stars could be calculated with these by inputting the location of
the observer on the meridian ring of the globe.

In the 12th century, Jabir ibn Aflah (Geber) was "the first to design a portable celestial sphere to measure
and explain the movements of celestial objects."






Seamless celestial globe



The seamless celestial globe invented by Muslim metallurgists and instrument-makers in Mughal India, specifically Lahore and Kashmir, is considered to be one of the most remarkable feats in metallurgy and engineering. All globes before and after this were seamed, and in the 20th century, it was believed by metallurgists to be technically impossible to create a metal globe without any seams.

It was in the 1980s, however, that Emilie Savage-Smith discovered several celestial globes without any
seams in Lahore and Kashmir.

The earliest was invented in Kashmir by the Muslim metallurgist Ali Kashmiri ibn Luqman in 998 AH (1589-90 CE) during Akbar the Great's reign; another was produced in 1070 AH (1659-60 CE) by Muhammad Salih Tahtawi with Arabic and Sanskrit inscriptions; and the last was produced in Lahore by a Hindu metallurgist Lala Balhumal Lahuri in 1842 during Jagatjit Singh Bahadur's reign. 21 such globes were produced, and these remain the only examples of seamless metal globes. These Mughal metallurgists developed the method of lost-wax casting in order to produce these globes.

These seamless celestial globes are considered to be an unsurpassed feat in metallurgy, hence some consider this achievement to be comparable to that of the Great Pyramid of Giza which was considered an unsurpassed feat in architecture until the 19th century.
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