Database: Astronomical Instruments

Astrolabe / 9th century, North Africa

Long before the invention of the telescope, ancient civilizations developed ways to chart the heavens. Building on their knowledge, Abbasid scholars improved their methods and created instruments still in use today.

The most important, and perhaps the most long-lived, was the astrolabe. It was created in the third century BCE by Greek astronomers as a way to "hold the universe in the palm of your hand". An astrolabe is indeed an engraved circle representing the stars rotating (in the Pre-Copernican geocentric thinking of the time) around the Earth. A circle in the middle of an astrolabe represents the user, set on a line that represents the horizon. Various points indicate known stars. From the eighth century onwards, Abbasid astronomers improved the astrolabe by adcing elements for deciphering the date and tour of the day, or other engraved disks pointing to the stars that could be seen at different latitudes for use by travellers.

This apparatus had many uses: determining the time of rising and setting of the sun and stars, calculating the height of buildings or the length of river crossings, and finding prayer time or the direction of Mecca. Abbasid astronomers found hundreds, if not thousands, of different ways to use this handy instrument!