Links Through Space: THE AGE OF ASTRONOMY: 2/7 Relics: Abù Bakr Ibn Yùsuf's medieval Moroccan astrolabes 1216AD

ANCIENT ASTRONOMY: THE AGE OF ASTRONOMY.

2/7: Relics: Abù Bakr Ibn Yùsuf's medieval Moroccan astrolabes 1216AD

What is the age of Astronomy? How old is it? Can we find some tangible evidence of it's age?

Many clues can be found in almost all civilizations on Earth before us.

In this mini series of articles we will establish the chronology of astronomy with astronomical relics, instruments, artifacts, alignments, maps, references and places in ancient periods pinpointing exactly in time, the age of Astronomy.

Ancient Astronomy Series. List of articles:

1/7 Instruments: NASA's STEREO mission. Predicting the Sun's activities. 2006AD

2/7 : Relics: Abù Bakr Ibn Yùsuf's medieval Moroccan astrolabes. 1216AD

3/7: Places: El caracol, Mayan Observatory. 906AD

4/7: Artefacts: Nebra sky disk of North Germany. 1600BC

5/7: Astronomical References: The scarab and the Dung beetle. 1813BC

6/7: Alignments: Megaliths of Carnac, France. 3300BC

7/7: Maps: Prehistoric Starmap. 10500BC

Illustration 4: Ce magnifique astrolabe planisphérique est exposé au musée Paul-Dupuy de Toulouse.Il fut construit par Abû Bakr Ibn Yûsuf, l'an 613 de l'Hégire (1216-1217).Crédit : Photo by Nicolas Brodu, 2002-2006.

1216 AD. Abù Bakr Ibn Yùsuf's medieval Moroccan astrolabes.

Location: Africa.

Astrolabes are serious technological relics from the past. They are ancient computers in every sense.

In this article we will investigate an Moroccan astronomer Abù Bakr Ibn Yùsuf's medieval astrolabe. The astrolabes were design to calculate many different applications on one complex 10 cm in diameter ”giant pocket watch type” of apparatus. Undoubtedly essential to those who used them. Even more, the makers of these astrolabes had to have an extant knowledge of multiple natural science disciplines to be able to built these precise instruments. Astrolabes and astronomy were a big think in the golden age of Al Andalous in southern Iberia peninsula, making this astrolabe a special relic from the Islamic astronomy of the medieval times.

Abù Bakr Ibn Yùsuf was a Moroccan astronomer who lived between the 12th and the 13th century. He was part of the Moorish school of thought based in Al Andalous, which was led a century earlier by the notable astronomer from Toledo Abû Ishaq Ibrahim Zarqali. Abù Bakr lived and worked in Marrakesh at a time where the Koutoubia Mosque was still under construction. He has made many astrolabes, which 5 (that we know) remains to this date scattered in museums and private collections around the world. One of his astrolabes, which is the astrolabe in question from 1216 AD, was made for Abû Muhammad ‘Abd al-Haqq, a sayyid (nobleman), son of one of the rulers of the Almohad dynasty.

Illustration 5: A remarkable astrolabe mater made by the leading astrolabist of medieval Morocco. Abu Bakr Ibn Yusuf, dedicated to an Almohad prince, Abu Muhammad Abd Al-Haqq, in Marrakesh, in the year 603 Hijra (A.D. 1206/07). Cast brass, fitted with replacement plates and rete10 cm. diam. 11.5cm. height including throne. On astrolabes as historical sources see King, Synchrony, II, pp. 339-402.

An astrolabe (Greek: ἀστρολάβος astrolabos, "star-taker") is an elaborate inclinometer, historically used by astronomers, navigators, and astrologers. Its many uses include locating and predicting the positions of the Sun, Moon, planets, and stars, determining local time, given local latitude and vice versa, surveying, and triangulation. It was used in classical antiquity, the Islamic Golden Age, the European Middle Ages and Renaissance for all these purposes. In the Islamic world, it was also used to calculate the Qibla and to find the times for Salat, prayers.

Illustration 6: Detailed elements of an astrolabe. Construction and use. Credit: Illustration of elements of astrolabe. Not mentioned.

Construction:

An astrolabe consists of a disk, called the mater (mother), which is deep enough to hold one or more flat plates called tympans, or climates. A tympan is made for a specific latitude and is engraved with a stereographic projection of circles denoting azimuth and altitude and representing the portion of the celestial sphere above the local horizon. The rim of the mater is typically graduated into hours of time, degrees of arc, or both. Above the mater and tympan, the rete, a framework bearing a projection of the ecliptic plane and several pointers indicating the positions of the brightest stars, is free to rotate. Some astrolabes have a narrow rule or label which rotates over the rete, and may be marked with a scale of declinations.

The rete, representing the sky, functions as a star chart. When it is rotated, the stars and the ecliptic move over the projection of the coordinates on the tympan. One complete rotation corresponds to the passage of a day. The astrolabe is therefore a predecessor of the modern planisphere.

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 calendar for converting the day of the month to the sun's position on the ecliptic, trigonometric scales, and a graduation of 360 degrees around the back edge. The alidade is attached to the back face. 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 (Star taker).

The construction of such an astrolabe demanded a huge mastery of multiple scientific disciplines. Spherical trigonometry, geometry, knowledge of the motion of stars, geography, chemistry, metallurgy and also astrology. The astrolabes of Abù Bakr Ibn Yùsuf are the legacy of an era where Arab enlightenment in natural sciences was the envy of the rest of the world.

In these few last paragraphs, one can really see the astronomy behind astrolabes. It is without a doubt that these trinkets were treasured and used extensively by there owners, which brought forward the knowledge of astronomy in that period of time.

So what is the age of Astronomy, you ask? At least since 1216 AD. That means the knowledge of astronomy is at least 799 years old.

The search for the age of Astronomy is still out there. Read the next article of our series on The age of Astronomy and see how far back we can push it's age in time. Stay tuned, and continue reading Ancient Astronomy Series: THE AGE OF ASTRONOMY.

Next Article: THE AGE OF ASTRONOMY. 3/7 Places: El Caracol, Chichen Itza, present Mexico. 906 AD.

Please take time to read the links and PDF files on this subject.

Links:

http://www.lopinion.ma/def.asp?codelangue=23&id_info=40828 (In french)

http://astrokech.blogspot.fi/2015/08/sortie-culturelle-rabat-la-decouverte.html

http://english.islammessage.com/ArticleDetails.aspx?articleId=2434 (story of Al Andalus)

http://taggedwiki.zubiaga.org/new_content/036b53806e080b2aa110e10e481d8725 (astrolabe)

http://wikipedia.unicefuganda.org/latest/A/Astrolabe.html

http://www.wikiwand.com/en/Astrolabe

http://www.sothebys.com/en/auctions/ecatalogue/2007/arts-of-the-islamic-world-l07220/lot.51.lotnum.html

http://astrokech.blogspot.fi/2014/11/resurrection-du-savant-abu-bakr-ibn.html (In French)

http://www.astrolabes.org/pages/parts.htm