i.3.1 Some Muslim Astronomical Observations

Muslim scholars were seeking the physically configuration of the Universe, that would be consistent with both mathematical and physical principles, unlike the Greek tradition where the mathematical astronomy, represented by Ptolemy, was considered separately from philosophical cosmology, represented by Aristotle. Therefore, Muslim astronomers and philosophers began questioning the technical details of the Ptolemaic system of astronomy. In the early 11th century, Ibn al-Haytham (Latinized: Alhazen, 965 1037) wrote his article On the Light of the Moon , which was the first successful attempt that combined mathematical astronomy with physics and applied the experimental method to astronomy and astrophysics, and formulated the relationship between an ideal mathematical model and the complex of observable phenomena. Some other astronomers discussed whether the Earth is moving, and considered how this might be consistent with astronomical computations and physical systems. Other Muslim astronomers, from the Maragha school of astronomy, developed non-Ptolemaic planetary models within a geocentric context that were later adapted by the Copernican model in a heliocentric context. In the 12th century, Averroes rejected the eccentric deferents introduced by Ptolemy, arguing for a strictly concentric model of the Universe [11].

Alhazen also was the first astronomer who conducted many observations and determined that the Milky Way had no parallax, concluding that it is very remote from the Earth and did not belong to the atmosphere [15], while al-Biruni (973 1048) proposed that it is a collection of countless fragments of the nature of nebulous stars. Al-Sufi (known in the West as Azophi) was also the first to observe the Andromeda Galaxy, and he described it as a small cloud. He also identified the Large Magellanic Cloud, which is visible from Yemen, and he published his findings in his Book of Fixed Stars in 964.

In 850, in his book A compendium of the science of stars , al-Farghani summarized the earlier Ptolemic cosmography, and then corrected Almagest based on findings of earlier Iranian astronomers, giving revised values for the obliquity of the ecliptic, the precessional movement of the apogees of the Sun and the Moon, and the circumference of the Earth. This and many other famous astronomical books were widely circulated through the Muslim world, and later translated into Latin.

Also in contrast to ancient Greek philosophers, who believed that the Universe had an infinite past with no beginning, medieval philosophers and theologians developed the concept of the Universe having a finite past with a beginning in time, known as temporal finitism. They used two logical arguments against an infinite past, the first being the argument from the impossibility of the existence of an actual infinite , and the second is the argument from the impossibility of completing an actual infinite by successive addition . Both arguments were adopted by later Western philosophers and theologians, and the second argument in particular became more famous after it was adopted by Kant in his thesis of the first antinomy concerning time.

In his Incoherence of the Philosophers, Al-Ghazali defended the Ashaari doctrine of a created Universe that is temporally finite, against the Aristotelian doctrine of an eternal Universe. In doing so, he proposed the modal theory of possible worlds, arguing that their actual world is the best of all possible worlds from among all the alternate time-lines and world histories that God could have possibly created.