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Yaʿqūb ibn Ṭāriq (; died c. 796 AD) was an 8th-century Persian astronomer and mathematician who lived in Baghdad. == Works == Works ascribed to Yaʿqūb ibn Ṭāriq include:〔Plofker〕 * ''Zīj maḥlūl fī al‐Sindhind li‐daraja daraja'' (, "Astronomical tables in the ''Sindhind'' resolved for each degree"), * ''Tarkīb al‐aflāk'' (, "Arrangement of the orbs"), * ''Kitāb al‐ʿilal'' (, "Rationales"), * ''Taqṭīʿ kardajāt al‐jayb'' (, "Distribution of the ''kardajas'' of the sine"), and * ''Mā irtafaʿa min qaws niṣf al‐nahār'' (, "Elevation along the arc of the meridian"). An astrological work called ''Al‐maqālāt'' (, "The Chapters") is also ascribed to him by an unreliable source.〔 The ''Zīj'', written around 770, was based on a Sanskrit work,〔 thought to be similar to the ''Brāhmasphuṭasiddhānta''.〔Pingree, p. 97〕 This work was brought to the court of al-Mansūr from Sindh,〔 reportedly by an Sindhi astronomer named Kankah.〔Kennedy 1956, p. 134, 71〕 The ''Tarkīb al‐aflāk'' dealt with cosmography, that is, the placement and sizes of the heavenly bodies.〔 Its estimates of the sizes and distances of the heavenly bodies were tabulated in al-Bīrūnī's work on India; according to him, Yaʿqūb ibn Ṭāriq gave the radius of the Earth as 1,050 ''farsakhs'', the diameter of the Moon and Mercury as 5,000 farsakhs (4.8 Earth radii), and the diameter of the other heavenly bodies (Venus, the Sun, Mars, Jupiter, and Saturn) as 20,000 ''farsakhs'' (19.0 Earth radii.)〔Pingree, pp. 105–106〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Yaʿqūb ibn Ṭāriq」の詳細全文を読む スポンサード リンク
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