Astronomy no doubt started in Islamic science by Arabic translation of Indian treatise “Sidhanta” in Baghdad in 155 AH/771 AD. Soon Arabic translation of Sassanid work “Astronomical Table of the King” was available to Islamic astronomers. Then Ptolmy’s “Almagest” and other Greek works of the school of Alexandria caught the attention of Islamic astronomers. As Ptolmy tried to explain the planetary motions making the earth as center so there were lot of contradictions which were finally resolved by Islamic scientists Ibn al-Shatir in 8th century AH (14 century AD).
As the Islamic scientists were in general efficient in experimental sciences and development of instruments of measurement, so Islamic astronomers corrected Hellenistic numerical values for astronomical quantities, including the obliquity of the ecliptic (i.e. the angle between the sun’s apparent path, the ecliptic and the celestial equator). These values were so accurate that these proved valid when geo centric model of universe was replaced by heliocentric or sun centered model. Islamic astronomers also discussed practical problems of the calendar, time and finding of ‘Qibla’ (Direction of Ka’ba). The accurate ‘Qibla’ tables of the Syrian astronomer al-Khalili (8th century AH/AD 14th century) were soon available.