Astronomy (Arabic 'ilm al-falak or 'ilm al-hay'a) is the natural science concerned with celestial objects — stars, planets, moons, comets — and the physical structure and evolution of the cosmos. Within the CSS Islamic Studies syllabus it is studied chiefly as a domain of the Muslim contribution to science, where astronomy held a privileged status because it served religious obligations: determining the qibla (direction of the Ka'ba), fixing prayer times (awqāt al-ṣalāh), and sighting the new moon (ru'ya al-hilāl) to establish the lunar Hijri calendar. The Qur'anic injunctions invoking the sun, moon and stars as signs (āyāt) — for example Sūrah Yā-Sīn 36:38–40 and Sūrah al-Anʿām 6:97 — provided theological motivation for observational precision.
Muslim astronomy crystallised in the ninth century through the translation movement at the Bayt al-Ḥikma (House of Wisdom) under the Abbasid caliphs al-Maʾmūn and al-Manṣūr, where Ptolemy's Almagest and Indian Siddhānta texts were rendered into Arabic. Astronomers then moved beyond translation to original observation and critique. Al-Khwārizmī (d. c. 850) compiled the Zīj al-Sindhind astronomical tables; al-Battānī (Albategnius, d. 929) refined the length of the solar year and the precession of the equinoxes; al-Ṣūfī (d. 986) catalogued the fixed stars in his Book of Fixed Stars, recording the Andromeda nebula. Al-Bīrūnī (d. 1048) measured the Earth's radius and discussed the possibility of heliocentrism, while the Marāgha school under Naṣīr al-Dīn al-Ṭūsī (d. 1274), with its "Ṭūsī couple," produced non-Ptolemaic planetary models later echoed in Copernicus. The instruments of the discipline — the astrolabe, quadrant, armillary sphere and sundial — and great observatories such as Ulugh Beg's at Samarkand (1420s), which yielded the Zīj-i Sulṭānī, mark the empirical apex of the tradition.
The lasting legacy survives in nomenclature: hundreds of star names remain Arabic in origin — Aldebaran, Betelgeuse, Rigel, Vega, Deneb — and terms such as zenith, azimuth and almanac entered European languages through Arabic. After the medieval flowering, leadership in astronomy passed to early-modern Europe with Copernicus, Kepler, Galileo and Newton, and the modern science is governed institutionally by bodies like the International Astronomical Union (founded 1919), which standardises nomenclature and in 2006 reclassified Pluto as a dwarf planet. In 2026, astronomy continues through observatories such as the James Webb Space Telescope and ground-based facilities, while Islamic calendrical astronomy still informs the official hilāl determinations of Muslim-majority states.
For the CSS examination, astronomy appears in Islamic Studies under the theme "Muslim Contribution to Science and Civilisation," and candidates are expected to name scholars, their works, and specific innovations with accuracy. A typical question asks candidates to "Discuss the contribution of Muslim scholars to astronomy" or to evaluate the religious imperatives that drove the science. High-scoring answers cite dated figures (al-Battānī, al-Bīrūnī, Ulugh Beg), institutions (Bayt al-Ḥikma, Marāgha, Samarkand observatory), and the transmission of knowledge to Renaissance Europe, linking empirical achievement to Qur'anic encouragement of reflection upon creation.
Example
In the 1420s, the Timurid ruler and astronomer Ulugh Beg built a great observatory at Samarkand and compiled the Zīj-i Sulṭānī star catalogue, the most accurate of its age before the telescope.
Frequently asked questions
Astronomy served essential religious functions: determining the qibla toward the Ka'ba, calculating the five daily prayer times, and sighting the new moon to fix the lunar Hijri calendar. This practical and devotional necessity drove Muslim scholars toward observational precision and mathematical refinement.