Instruments & Observatories of Medieval Islamic Astronomy

Medieval Islamic astronomy was an amalgamation and extension of foreign influences, including Greek and Indian astronomy. Islamic astronomy itself went on to influence later discoveries, especially those in Europe and China. Numerous star names (Aldebaran, for example) and astronomical terms (such as azimuth) still in use today are of Islamic origin.

The peak of medieval Islamic astronomy came between the 8th and 15th Centuries CE. Developments took place throughout Islam’s sphere of influence, from the Middle East and Central Asia to North Africa, India, and the Far East. Roughly 10,000 medieval Islamic manuscripts on astronomy still exist today.

Inventions & Advances in Astronomy Instruments

Though the astrolabe was an ancient Greek invention for charting the stars, Islamic astronomer Fazari is credited with vastly improving the device. Examples of these improved astrolabes date back as far as 315 CE. During the Abbasid caliphate, Muslim scientists perfected the astrolabe to help chart the official beginning of Ramadan, the hours of prayer, and the relative direction of Mecca. A variation of the astrolabe, called the saphea, was devised by al-Zargali of Andalusia—this device could be used anywhere, independent of the user’s latitude.

Celestial globes, similar to standard globes but showing the apparent positions of stars in the sky, were first developed by Islamic astronomers and date back to at least the 11th Century. A related device, called the armillary sphere, consisting of a spherical framework of rings which represent lines of celestial longitude and latitude, the ecliptic, and other important astronomical features, was also a medieval Islamic invention.

A modern armillary sphere.

A modern armillary sphere.

The equatorium, a mechanical device that helps plot the positions of the moon, sun, and planets without calculation, was invented in roughly 1015 by astronomers in Al-Andalus (modern Spain, Portugal, Andorra, and southern France).

Medieval Islamic astronomers also invented numerous quadrants, including the sine quadrant (used for astronomical calculations) and several variations of the horary quadrant (used to determine time by observations of the sun or stars).

Major Observatories

In the medieval Islamic world, a number of private observatories existed in Baghdad, Damascus, and elsewhere. A number of astronomical advances were made from findings at these observatories, including the measurement of meridian degrees and solar parameters.

The first major observatory in the region was built in Isfahan (in modern Iran) in the 11th Century. From this observatory, Omar Khayyám and other scientists formulated the Persian Solar Calendar, a modernized version of which is still in use in Iran today.

The largest and most significant observatory was created in Maragha (also in modern Iran) in the 13th Century. The Mongol ruler Hulagu Khan kept a home there, and the structure also housed a mosque and library. Numerous leading astronomers of the time worked there, and over the course of a half-century, developed a number of key modifications to the Ptolemaic system.

Another major observatory, now known as the Istanbul Observatory of Taqi ad-Din, was built in 1577. It lasted three years later, however. A large, long-tailed comet was observed and prognosticated to be a sign of coming good fortune; instead, a plague followed, after which spiritually-minded opponents of science and prognostication from the heavens called for the observatory’s destruction.

Photo credit: francisco.j.gonzalez / Foter / Creative Commons Attribution 2.0 Generic (CC BY 2.0)

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