SHAFAQNA- This is the fourth article of a series that will be focused on influential Muslim scientists. To see if any other articles have been uploaded, search the tag or keywords ‘Muslim scientists’
Muslims made significant contributions in the field of astronomy which is greatly acknowledged in the history texts, “Since the modern scientific revolution of Europe in the sixteenth and seventeenth centuries is generally centered on developments in astronomy and the philosophical implications of the works of Copernicus (specially as taken up by Galileo), it is useful to consider the history of astronomical thinking in medieval Islam. For astronomical work in Islam during this period was both intense and far in advance of equivalent thoughts in Europe.” 
According to Howard R Turner, Muslims began the organized and detailed observations of the skies soon after the early expansion of Islam. This effort was naturally accelerated by an increasing demand for precise tables needed in preparing calendars, prayer tables. A number of observatories were established at centers such as Rayy, Isfahan, and Shiraz in Persia as well as in Egypt…two particularly impressive observatories, with large professional staffs, were established, one in the thirteenth century at Maragha, in Persia, the other in the fifteenth century at Samarkand, in what is now Uzbekistan.
The first Muslim astronomers who emerged in eighth century in Baghdad based their astronomical works basically on Persian and Indian astronomical tables. While laying the foundations for the city of Baghdad, the preliminary calculations were made with the help of Zij-e-Shahi, the Tables of King, which was an essentially a Persian product.
In the early part of ninth century Habash al-Hasib directed the composition of Mamunic astronomical tables. Abu Mashar from the same period composed “Great Introduction of Astrology” which was translated into Latin several times, and another eminent astronomer al-Farghani (Alfraganus) authored “Elements of Astronomy”. In the second half of ninth century Al-Nairizi (Anaritius) composed a great treatise on the spherical astrolabe and made wrote a commentary on Almagest. The contemporary of Al-Nairizi, Thabit ibn Qurrah is famous for upholding the theory of oscillatory motion of equinoxes. Thabit also added a ninth sphere to the eight of Ptolemaic astronomy. Following the Thabit ibn Qurrah’s line of study, another Muslim astronomer al-Battani (Albategnius) made some of most important contributions in Islamic astronomy. “He discovered the increase of the sun’s apogee since time of Ptolemy which led to the discovery of the solar apsides. He determined the precession as 54.5” a year, and inclination of the ecliptic as 23°35′. He also discovered a new method for determining the time of the vision of the new moon, and made a detailed study of the solar and lunar eclipses, used as late as eighteenth century by Dunthorn, in his determination of the gradual change in lunar motion. Al-Battanis major astronomical works, which also contains a set of tables, became known in the West as De Scientia Stellarum (On the Science of Stars); it was one of the basic works of astronomy down to the Renaissance.”
In the tenth century, the names of Abu Sahl al-Kuhi, Abd al-Rahman al-Sufi, Abu Said al-Sijzi, Abul Wafa al-Buzjani, and al-Kirmani are among the shining astronomers. Abd al-Rahman al-Sufi’s work entitled “Figures of the Stars” is regarded as one of the masterpieces of observational astronomy in Islam. Abu Said al-Sijzi constructed an astrolabe based on the motion of earth around the sun.
In the eleventh century al-Biruni contributed by determining latitudes and longitudes, performing geodetic measurements and other major astronomical measurements. Another astronomer from this period Ibn Yunus completed his Zij (Hakimite tables) in 1007 AD. In his tables he remeasured many constants accurately. For this contribution, the scholar G. Sarton regarded him as the most important among Muslim astronomers. Apart from astronomy, he made great contributions in mathematics also. He solved the problems of spherical trigonometry by means of orthogonal projections and studied isometric oscillatory motion of a pendulum, which later led to the construction of mechanical clocks.
In later half of the eleventh century, Spanish Muslim observational astronomer al-Zarqali invented a new astronomer instrument called Sahifah (Saphaea Arzachelis) and edited Toleden Zij.
In the twelfth century, an anti-Ptolemy trend set in to Spanish Muslim astronomers. The scholars like Jabir ibn Aflah and ibn Tufail criticized the Ptolemy model and proposed a system based solely on eccentric spheres. Later in thirteenth century, al-Bitruji who was student of ibn Tufail developed the concepts of his teacher and formed the theory of spiral motion. This resulted in rejection of Ptolemaic system by the Renaissance scientists.
In the Eastern lands of Islam, the great scholar Nasir al-Din al-Tusi severely criticized Ptolemy and introduced a new planetary model. This model, which was later completed by his student Qutub al-Din al-Shirazi, sought to lay more emphasis on the spherical nature of the heavens by placing the Earth at the geometric center of the heavenly spheres. Al-Tusi conceived two spheres rolling one within the other to explain the apparent motion of the planets. The American astronomer E.S. Kennedy named the planetary model as the “Tusi Couple” in al-Tusi’s honor. Al-Tusi’s student Qutub al-Din al-Shirazi developed the variation of this model for Mercury. And in the fourteenth century, Ibn al-Shatir completed the lunar model in his work entitled “A Text of the Final Inquiry in Amending the Elements”. Ibn al-Shatir introduced a second epicycle in both lunar and solar systems. The lunar theory proposed two centuries later by Copernicus is almost the same as that introduced by ibn al-Shatir. There is great probability that Copernicus was aware with ibn al-Shatir’s work through translations and followed ibn al-Shatir’s views in developing his theory. “In recent years historians of astronomy have become interested in the marked similarity between the models of epicyclic motion proposed by al-Tusi and ibn al-Shatir and one proposed three centuries later by…Copernicus.”  There is great likelihood that Copernicus borrowed ideas from al-Tusi and ibn al-Shatir.
In short, there are numerous examples of Muslim’s interest in astronomy. Their contributions are endless, but this article has listed a few. Science is nothing new to Islam and our faith encourages the study of such sciences–they not only help one in worldly matters of knowledge but contribute to a greater understanding of the self within this universe.
The Rise of Early Modern Science: Islam, China, and the West, Toby E. Huff
Science and Civilization in Islam, Seyyed Hossein Nasr
Science in Medieval Islam, Howard R. Turner