Yaʿqūb ibn Ṭāriq (; died AD) was an 8th-century

Persian Persian may refer to: * People and things from Iran, historically called ''Persia'' in the English language ** Persians, the majority ethnic group in Iran, not to be conflated with the Iranic peoples ** Persian language, an Iranian language of the ...

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...

and

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change. History On ...

who lived in

Baghdad Baghdad (; ar, بَغْدَاد , ) is the capital of Iraq and the second-largest city in the Arab world after Cairo. It is located on the Tigris near the ruins of the ancient city of Babylon and the Sassanid Persian capital of Ctesiphon ...

Works

Works ascribed to Yaʿqūb ibn Ṭāriq include:Plofker * (, "Astronomical tables in the ''Sindhind'' resolved for each degree") * (, "Arrangement of the orbs") * (, "Rationales") * (, "Distribution of the ''kardajas'' of the sine") * (, "Elevation along the arc of the meridian") An astrological work called (, "The Chapters") is also ascribed to Yaʿqūb ibn Ṭāriq by an unreliable source. Yaʿqūb ibn Ṭāriq's , written around 770, was based on a

Sanskrit Sanskrit (; attributively , ; nominally , , ) is a classical language belonging to the Indo-Aryan branch of the Indo-European languages. It arose in South Asia after its predecessor languages had diffused there from the northwest in the late ...

work, thought to be similar to the ''

Brāhmasphuṭasiddhānta The ''Brāhmasphuṭasiddhānta'' ("Correctly Established Doctrine of Brahma", abbreviated BSS) is the main work of Brahmagupta, written c. 628. This text of mathematical astronomy contains significant mathematical content, including a good unders ...

''.Pingree, p. 97 It was brought to the court of al-Mansūr from

Sindh Sindh (; ; ur, , ; historically romanized as Sind) is one of the four provinces of Pakistan. Located in the southeastern region of the country, Sindh is the third-largest province of Pakistan by land area and the second-largest province ...

, reportedly by a Sindhi astronomer named Kankah.Kennedy 1956, p. 134, 71 dealt with

cosmography The term cosmography has two distinct meanings: traditionally it has been the protoscience of mapping the general features of the cosmos, heaven and Earth; more recently, it has been used to describe the ongoing effort to determine the large-scal ...

(the placement and sizes of the heavenly bodies). The estimations of the sizes and distances of the heavenly bodies in were tabulated in the 11th century by

al-Bīrūnī Abu Rayhan Muhammad ibn Ahmad al-Biruni (973 – after 1050) commonly known as al-Biruni, was a Khwarazmian Iranian in scholar and polymath during the Islamic Golden Age. He has been called variously the "founder of Indology", "Father of Co ...

, in a work on India. According to al-Bīrūnī, Yaʿqūb ibn Ṭāriq gave the

radius of the Earth Earth radius (denoted as ''R''🜨 or R_E) is the distance from the center of Earth to a point on or near its surface. Approximating the figure of Earth by an Earth spheroid, the radius ranges from a maximum of nearly (equatorial radius, deno ...

as 1,050 , the diameter of the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

and

Mercury Mercury commonly refers to: * Mercury (planet), the nearest planet to the Sun * Mercury (element), a metallic chemical element with the symbol Hg * Mercury (mythology), a Roman god Mercury or The Mercury may also refer to: Companies * Merc ...

as 5,000 (4.8 Earth radii), and the diameter of the other heavenly bodies (Venus, the Sun, Mars, Jupiter, and Saturn) as 20,000 (19.0 Earth radii).Pingree, pp. 105–106

Works

Notes

Further reading