Muslims have always had a special interest in astronomy. The moon and the sun are of vital importance in the daily life of every Muslim. By the moon, Muslims determine the beginning and the end of the months in their lunar calendar. By the sun the Muslims calculate the times for prayer and fasting. It is also by means of astronomy that Muslims can determine the precise direction of the Qiblah, to face the Ka’bah in Makkah, during prayer. The most precise solar calendar, superior to the Julian, is the Jilali, devised under the supervision of Umar Khayyam. The Qur’an contains many references to astronomy.
“The heavens and the earth were ordered rightly, and were made subservient to man, including the sun, the moon, the stars, and day and night. Every heavenly body moves in an orbit assigned to it by God and never digresses, making the universe an orderly cosmos whose life and existence, diminution and expansion, are totally determined by the Creator.” [Qur’an 30:22]
These references, and the injunctions to learn, inspired the early Muslim scholars to study the heavens. They integrated the earlier works of the Indians, Persians and Greeks into a new synthesis. Ptolemy’s Almagest (the title as we know it is Arabic) was translated, studied and criticized. Many new stars were discovered, as we see in their Arabic names – Algol, Deneb, Betelgeuse, Rigel, Aldebaran. Astronomical tables were compiled, among them the Toledan tables, which were used by Copernicus, Tycho Brahe and Kepler. Also compiled were almanacs – another Arabic term. Other terms from Arabic are zenith, nadir, albedo, azimuth.
Muslim astronomers were the first to establish observatories, like the one built at Mugharah by Hulagu, the son of Genghis Khan, in Persia, and they invented instruments such as the quadrant and astrolabe, which led to advances not only in astronomy but in oceanic navigation, contributing to the European age of exploration.