Abu al-Tayyib Sanad ibn Ali al-Yahudi (died c. 864 C.E.), was a ninth-century Iraqi Jewish astronomer, translator, mathematician and engineer employed at the court of the Abbasid caliph

Al-Ma'mun Abu al-Abbas Abdallah ibn Harun al-Rashid ( ar, أبو العباس عبد الله بن هارون الرشيد, Abū al-ʿAbbās ʿAbd Allāh ibn Hārūn ar-Rashīd; 14 September 786 – 9 August 833), better known by his regnal name Al-Ma'mu ...

. A later convert to

Islam Islam (; ar, ۘالِإسلَام, , ) is an Abrahamic religions, Abrahamic Monotheism#Islam, monotheistic religion centred primarily around the Quran, a religious text considered by Muslims to be the direct word of God in Islam, God (or ...

, Sanad's father was a learned Jewish astronomer who lived and worked in Baghdad.

Biography

He is known to have translated and modified the Zij al-Sindhind. The Zij al-Sindhind was the first astronomical table ever introduced in the Muslim World. As a mathematician Sanad ibn ʿAlī was a colleague of al-Khwarizmi and worked closely with Yaqūb ibn Tāriq together they calculated the diameter of the Earth and other astronomical bodies. He also wrote a commentary on '' Kitāb al-ğabr wa-l-muqābala'' and helped prove the works of al-Khwarizmi. The decimal point notation to the

Arabic numerals Arabic numerals are the ten numerical digits: , , , , , , , , and . They are the most commonly used symbols to write Decimal, decimal numbers. They are also used for writing numbers in other systems such as octal, and for writing identifiers ...

was introduced by Sanad ibn Ali. According to Ibn Abi Usaibia: the

Banū Mūsā The Banū Mūsā brothers ("Sons of Moses"), namely Abū Jaʿfar, Muḥammad ibn Mūsā ibn Shākir (before 803 – February 873); Abū al‐Qāsim, Aḥmad ibn Mūsā ibn Shākir (d. 9th century); and Al-Ḥasan ibn Mūsā ibn Shākir (d. 9th ce ...

brothers out of sheer professional jealousy kept him away from

Abbasid Caliph The Abbasid caliphs were the holders of the Islamic title of caliph who were members of the Abbasid dynasty, a branch of the Quraysh tribe descended from the uncle of the Islamic prophet Muhammad, Al-Abbas ibn Abd al-Muttalib. The family came t ...

al-Mutawakkil Abū al-Faḍl Jaʿfar ibn Muḥammad al-Muʿtaṣim bi-ʾllāh ( ar, جعفر بن محمد المعتصم بالله; March 822 – 11 December 861), better known by his regnal name Al-Mutawakkil ʿalā Allāh (, "He who relies on God") was t ...

at his new capital

Samarra Samarra ( ar, سَامَرَّاء, ') is a city in Iraq. It stands on the east bank of the Tigris in the Saladin Governorate, north of Baghdad. The city of Samarra was founded by Abbasid Caliph Al-Mutasim for his Turkish professional army ...

and had caused Sanad ibn ʿAlī to be sent away to Baghdad. Both Ja'far Muhammad ibn Mūsā ibn Shākir and Ahmad ibn Mūsā ibn Shākir delegated the work of digging a great canal instead to Al-Farghani and thus ignoring Sanad ibn ʿAlī, the better engineer. Al-Farghani committed a great error, making the beginning of the canal deeper than the rest and water never reached the new garrison of ''Al-Ja'fariya''. News of this greatly angered

and the two

brothers were saved from severe punishment only by the gracious willingness of Sanad ibn ʿAlī, to vouch the corrections of Al-Farghani's calculations thus risking his own welfare and possibly his life.

References

{{DEFAULTSORT:Ibn Ali, Sind Astronomers from the Abbasid Caliphate Astronomers of the medieval Islamic world Mathematicians from the Abbasid Caliphate Medieval engineers Year of death unknown 9th-century people from the Abbasid Caliphate Year of birth unknown 9th-century translators Converts to Islam from Judaism 9th-century Jews Jews from the Abbasid Caliphate