The study of the heavens is as old as humanity. Long before clocks and calendars, humans turned to the heavens to measure time and orient themselves on the planet by observing cycles related to the motions of Earth, Sun, Moon, and the stars to determine the length of days, months, and years.
Among the various ancient tools to study the heavens, the astrolabe is among the most sophisticated scientific instrument ever made. From the Greek astro meaning ‘star,’ and labe meaning ‘finder,’ the astrolabe was used to determine the positions of celestial bodies in terms of celestial latitudes and longitudes, combined with slide rule-like features that allowed other calculations.
Invented by the Greeks in about the second or third century BCE, the astrolabe was further advanced by scientists and scholars in the medieval Islamic region in the eighth to eleventh centuries CE. The Arab treatises on the astrolabe published in the ninth century indicate their familiarity with the instrument, which was inherently valuable in Islam due to its ability to determine the time of day for prayers, as well as direction of Mecca. A key instrument in the Middle Ages, the astrolabe was also used to measure the height of buildings as well as for other calculations and observations. Essentially it was a device that could do everything: “Give you the time, your location, your horoscope, and even help you make decisions—all with the swipe of a hand” (Poppick, Smithsonian Magazine).
A prominent, skillful builder of astrolabes, Maryam Al-Ijliya, also known as Maryam Al-Astrulabi, was born in the tenth century in Aleppo, Syria. Mariam’s interest in developing astrolabes grew when she saw her father, known as Al-Ijliyy al-Asturlabi, building them, having apprenticed with an astrolabe maker in Baghdad. Her masterful skill of making astrolabes impressed the ruler of the Emirate of Aleppo, Sayf al-Dawla [r. 944 to 967 CE], who employed her in his court (Aga Khan Museum). Mariam’s significant contributions in the field of astronomy were recognised when the main-belt asteroid 7060 Al-‘Ijliya, discovered by Henry E. Holt at Palomar Observatory (San Diego, USA) in 1990, was named after her.
The astrolabe was introduced into Europe through North Africa and al-Andalus (medieval Muslim-ruled Spain) as early as the eleventh century, through translation of Arabic work; its use was not widespread until the thirteenth century, with peak usage in the fifteenth and sixteenth centuries.
In the eighth century, the scientific and philosophical legacy of the ancient world was translated into Arabic at the House of Wisdom (Bayt al-Hikma) in Baghdad. By the tenth century, much of the Hellenistic intellectual legacy as well as materials from ancient Iran and India were available in Arabic.
In the the twelfth and thirteenth centuries, another transfer of knowledge took place, this time from Arabic into Latin, at Toledo, Spain. It was “a centre of what has been called the “convivencia,” the time in Spain when Muslims, Jews, and Christians lived together and got along without living in a constant state of opposition and war” (Bentley, Aga Khan Museum). This resulted in a significant portion of Islamic philosophical and scientific learning made available to medieval European scholars.
The first college of translators from Arabic into Latin was established by Don Raimundo, the Archbishop of Toledo from 1126 to 1151. A Benedictine monk, Raimundo was convinced of the importance of the Arab philosophers’ understanding of Aristotle’s works, and decided to make their works available in Latin.
Among the prominent Toledan translators was Gerard of Cremona (1114-1187). Thanks to a brief note left by his pupils on his life and work, we know that Gerard came to Toledo after finishing his studies in Italy, in order to learn more about the Almagest. This vast astronomical treatise by Claudius Ptolemaeus (Ptolemy), the celebrated second-century Greek astronomer, mathematician and geographer, was only available in Arabic at that time. In Toledo, Gerard discovered a multitude of scientific works in Arabic and began to learn the language so as to read them and, later, to render them into Latin. Hence, Latin names were engraved alongside the Arabic words on the astrolabes; it seems likely that the use of Arabic star names in Europe was influenced by the importing of these instruments. Muslim Spain played an important role in the transmission of astronomical and other fields of knowledge to Europe.
Mawlana Hazar Imam Aga Khan IV noted this enabling environment in his address upon receiving the Royal Toledo Award (2 March 2006) for work in the preservation and revitalisation of historic cities in the Islamic world:
“… Toledo… has so successfully preserved, over many centuries, the evidence of its three-fold culture: magnificent churches, synagogues, and mosques. This was an era when each of these cultures, Christian, Jewish, and Muslim, retained its independent identity while all worked and came together in a glorious intellectual and spiritual adventure. The legacy was a truly enabling environment conducive to prosperity, harmony, scientific discovery, philosophical insights, and artistic flowering – all the defining features of a thriving civilisation.”
The planispheric astrolabe initially consisted of six parts including the latitude plate which was made for specific latitudes. Ibrahim al-Zarqali (d. 1087), known as Azarchel in the West, introduced a universal plate capable of calculations at any latitude, thereby rendering the astrolabe usable in any part of the world, essentially serving as a GPS.
The compact versatile nature of the astrolabe made it the most treasured instrument for astronomers. “This somewhat-scientific, somewhat-mystical device leaves its traces in modern analog gadgets like a slide rule or the fanciest Swiss watches” (Poppick, Smithsonian Magazine). The use of the astrolabe declined in the late seventeenth century with the invention of the pendulum clock and the telescope.
Abdurrahman Badawi, The Toledo School, UNESCO Courier, December 1991
Charvi Kathuria, Tech Women: Meet Mariam Astrulabi, The Woman Behind Astrolabes, shethepeople
Laura Poppick, The Story of the Astrolabe, the Original Smartphone, Smithsonian Magazine
Patricia Bentley, Planispheric Astrolabe, Aga Khan Museum
Robert A. Egler, Measuring the Heavens: Astronomical Instruments Before the Telescope, Astrophysics Data System
Thomas Burman, “Islam in Spain and Western Europe” published in The Muslim Almanac Edited by Azim A. Nanji, Gale Research Inc., Detroit, 1996
Contributed by Nimira Dewji. Nimira is an invited writer although she has contributed several articles in the past (view previous articles). She also has her own blog – Nimirasblog – where she writes short articles on Ismaili history and Muslim civilisations. When not researching and writing, Nimira volunteers at a shelter for the unhoused and at a women’s shelter. She can be reached at firstname.lastname@example.org