Islamic Contributions to Astronomy

Muslim astronomers made transformative contributions to the science of astronomy from the 8th to the 16th century CE. Their work was motivated by both intellectual curiosity and practical Islamic needs: determining the qiblah (direction of prayer) from any location, calculating prayer times based on the sun's position, establishing the beginning and end of lunar months for Ramadan and Hajj, and navigating for trade and Hajj pilgrimages. The Quran itself encourages the study of the heavens: "Indeed, in the creation of the heavens and the earth and the alternation of the night and the day are signs for those of understanding" (Quran 3:190).

Major Astronomers and Their Contributions

Al-Khwarizmi (d. 850 CE) produced astronomical tables (zij) that were used for centuries to calculate the positions of celestial bodies. Al-Battani (d. 929 CE) improved Ptolemy's measurements of the solar year and the obliquity of the ecliptic with remarkable accuracy. Ibn al-Haytham (d. 1040 CE), known primarily for his work in optics, also critiqued Ptolemaic astronomy and proposed physical models for celestial motion. Al-Biruni (d. 1048 CE) calculated the Earth's radius to within 1% of its actual value and discussed the possibility of Earth's rotation. Nasir al-Din al-Tusi (d. 1274 CE) developed the Tusi couple, a mathematical device that influenced Copernicus's later heliocentric model.

Observatories

Muslim rulers established the world's first large-scale astronomical observatories as permanent research institutions. The Shammasiyya observatory in Baghdad (built by al-Ma'mun in 828 CE), the Maragha observatory in Persia (built by Hulagu Khan for al-Tusi in 1259 CE), and the Samarkand observatory of Ulugh Beg (1420 CE) were centers of collaborative research with sophisticated instruments. These observatories produced star catalogs, planetary tables, and theoretical models that were more accurate than anything produced in Europe until the Renaissance. The concept of a permanent, state-funded observatory itself was a Muslim innovation.

Instruments

Muslim astronomers developed and refined numerous instruments. The astrolabe, adapted from Greek designs and vastly improved, became the Swiss army knife of medieval astronomy: it could determine prayer times, find the qiblah, measure the height of stars and buildings, and serve as a navigational tool. The quadrant, the sextant, the armillary sphere, and the celestial globe were all developed or enhanced by Muslim scientists. Many astronomical terms in European languages derive from Arabic: zenith (samt), nadir (nazir), azimuth (al-samt), and the names of many stars (Aldebaran, Altair, Betelgeuse, Rigel, Vega) are all Arabic words.