Ya'qub ibn Tariq

Yaʿqūb ibn Ṭāriq was active in Baghdad as an astronomer during the rule of the second Abbasid caliph, al-Manṣūr (r. 754–775).

[2] Yaʿqūb ibn Ṭāriq's treatise Tarkīb al‐aflāk dealt with cosmography (the placement and sizes of the heavenly bodies).

[4] The estimations of their sizes and distances in Tarkīb al‐aflāk were tabulated in the 11th century by the polymath al-Bīrūnī, in his work on India.

[1] The Christian astrologer Ibn Hibintā mentioned Yaʿqūb, noting that he used the positions of the Sun and the stars to determine the latitude of places.

[4] Yaʿqūb ibn Ṭāriq's zij, written in around 770, was based on a Sanskrit work,[4] thought to be similar to the Brāhmasphuṭasiddhānta.

William Muir 's depiction of the original round city of Baghdad (1883), where Yaʿqūb ibn Ṭāriq was active during his career