Banū Mūsā

The Banū Mūsā brothers ("Sons of Moses"), namely Abū Jaʿfar Muḥammad ibn Mūsā ibn Shākir (before 803 – 873), Aḥmad ibn Mūsā ibn Shākir (803 – 873) and Al-Ḥasan ibn Mūsā ibn Shākir (810 – 873), were three 9th-century Persian scholars of Baghdad who are known for their Book of Ingenious Devices on automata (automatic machines) and mechanical devices.

The Banu Musa were sons of Mūsā ibn Shākir, who had been a highwayman and later an astrologer and astronomer to the Caliph al-Maʾmūn. After his death, his young sons were looked after by the court of al-Harun's son, the caliph al-Maʾmūn. 

The brothers were given access to the famous House of Wisdom library and translation center in Baghdad. They participated in the efforts to translate ancient Greek works into Arabic by sending for Greek texts from the Byzantines, paying large sums for their translation, and learning Greek themselves.

They were mathematicians, expanding on Appolonius' work by writing on the mathematics of ellipses and cones. They were astronomers, correctly calculating the circumference of the earth when asked to do so by al-Mamun. 

Most notable among their achievements is their work in the field of automation, which they utilized in toys and other entertaining creations. Their Book of Ingenious Devices describes 100 such inventions; the ones which have been reconstructed work as designed. While designed primarily for amusement purposes, they employ innovative engineering technologies such as one-way and two-way valves able to open and close by themselves, mechanical memories, devices to respond to feedback, and delays. Most of these devices were operated by water pressure.

Ahmad ibn Muhammad ibn Kathīr al-Farghānī

Abū al-ʿAbbās Aḥmad ibn Muḥammad ibn Kathīr al-Farghānī also known as Alfraganus in the West was a Persian astronomer and one of the famous astronomers in 9th century.

He was involved in the calculation of the diameter of the Earth by the measurement of the meridian arc length together with a team of scientists under the patronage of al-Ma'mūn in Baghdad. His textbook Elements of astronomy on the celestial motions, written about 833, was a competent descriptive summary of Ptolemy's Almagest. It was translated into Latin in the 12th century and remained very popular in Europe until the time of Regiomontanus. Dante Alighieri's knowledge of Ptolemaic astronomy, which is evident in his Divina Commedia as well as other works such as theConvivio, seems to have been drawn from his reading of Alfraganus.  In the 17th century the Dutch orientalist Jacob Golius published the Arabic text on the basis of a manuscript he had acquired in the Near East, with a new Latin translation and extensive notes.

Later he moved to Cairo, where he composed a treatise on the astrolabe around 856. There he also supervised the construction of the large Nilometer on the island of al-Rawda (in Old Cairo) in the year 861.

The crater Alfraganus on the Moon is named after him.

Abu Ma'shar al-Balkhi

Abū Maʿshar, Jaʿfar ibn Muḥammad al-Balkhī (also known as al-Falakī or Ibn Balkhī, Latinized as Albumasar, Albusar, or Albuxar) (10 August 787 in Balkh, Khurasan – 9 March 886 in Wāsiṭ, Iraq), was a Persian astrologer, astronomer, and Islamic philosopher, thought to be the greatest astrologer of the Abbasid court in Baghdad. He was not a major innovator, and his works are practical books for training of astrologers; even as an astrologer he was not intellectually rigorous. He wrote a number of practical manuals on astrology that profoundly influenced Muslim intellectual history and, through translations, that of western Europe and Byzantium.

Muḥammad ibn Mūsā al-Khwārizmī

Abū ʿAbdallāh Muḥammad ibn Mūsā al-Khwārizmī (c. 780, Khwārizm – c. 850) was a Persian mathematician, astronomer and geographer, a scholar in the House of Wisdom in Baghdad.

In the twelfth century, Latin translations of his work on the Indian numerals, introduced the decimal positional number system to the Western world His Compendious Book on Calculation by Completion and Balancing presented the first systematic solution of linear and quadratic equations in Arabic. In Renaissance Europe, he was considered the original inventor of algebra, although we now know that his work is based on older Indian or Greek sources  He revised Ptolemy's Geography and wrote on astronomy and astrology.

Some words reflect the importance of al-Khwarizmi's contributions to mathematics. "Algebra" is derived from al-jabr, one of the two operations he used to solve quadratic equations. Algorism and algorithm stem from Algoritmi, the Latin form of his name.  His name is also the origin of (Spanish) guarismo and of (Portuguese) algarismo, both meaning digit.

Naubakht

Nobakht Ahvazi (Persian: نوبخت اهوازى, (or Naubakht Ahvaz) also transliterated 'Naubakht') and his sons were astrologers from Ahvaz (in the present-day Khuzestan Province of Iran).

Nobakht was particularly famous for having led a group of astrologers who picked an auspicious electional chart for the founding of Baghdad. His family also helped design the city. Originally Zoroastrians,Nobakht and his sons converted to Islam and were employed as Pahlavi translators of the Abbasid court.

Muḥammad ibn Ibrāhīm al-Fazārī

Abu abdallah Muhammad ibn Ibrahim al-Fazari (d. 796 or 806) was a Muslim philosopher, mathematician and astronomer He is not to be confused with his father Ibrāhīm al-Fazārī, also an astronomer and mathematician.

While some sources refer to him as an Arab, other sources state that he was a Persian.

Al-Fazārī translated many scientific books into Arabic and Persian He is credited to have built the first astrolabe in the Islamic world. 

Along with Yaʿqūb ibn Ṭāriq and his father he helped translate the Indian astronomical text by Brahmagupta (fl. 7th century), the Brāhmasphuṭasiddhānta, into Arabic as Az-Zīj ‛alā Sinī al-‛Arab., or the Sindhind. This translation was possibly the vehicle by means of which the Hindu numerals were transmitted from India to Islam.

Ibrāhīm al-Fazārī

Abu Ishaq Ibrahim ibn Habib ibn Sulaiman ibn Samura ibn Jundab al-Fazari (Arabic / Persian: أبو إسحاق إبراهيم بن حبيب بن سليمان بن سمورة بن جندب الفزاري) (d. 777 CE) was an 8th-century Muslim mathematician and astronomer of Persian background.

He was the mathematician and astronomer at the Abbasid court of the Caliph Harun al-Rashid. He is not to be confused with his son Muḥammad ibn Ibrāhīm al-Fazārī, also an Astronomer. He composed various astronomical writings ("on theastrolabe", "on the armillary spheres", "on the calendar").

The Caliph ordered him and his son to translate the Indian Astronomical text, The Sindhind along with Yaʿqūb ibn Ṭāriq, which was completed in Baghdad about 750 CE, and entitled Az-Zīj ‛alā Sinī al-‛Arab. This translation was possibly the vehicle by means of which the Hindu numerals were transmitted from India to Islam.

Yaʿqūb ibn Ṭāriq

Yaʿqūb ibn Ṭāriq (died c. 796 AD) was an 8th-century Persian astronomer and mathematician who lived in Baghdad.

Works ascribed to Yaʿqūb ibn Ṭāriq include:

• 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"),
• Taqṭīʿkardajāt 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 (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.  This work was brought to the court of al-Mansūr from Sind, reportedly by an Indian astronomer named Kankah. 

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.)

Ja'far al-Sadiq

Jaʿfar ibn Muhammad al-Sādiq (Arabic: جعفر بن محمد الصادق‎) (702-765 C.E. or 17th Rabī‘ al-Awwal 83 AH - 25th Shawwāl 148 AH) was a descendant of Muhammad and a prominent Muslim jurist. He is revered as an Imam by the adherents of Shi'a Islam and as a renowned Islamic scholar and personality by Sunni Muslims. The Shi'a Muslims consider him to be the sixth Imam or leader and spiritual successor to Muhammad.The internal dispute over who was to succeed Ja'far as Imam led to schism within Shi'a Islam. Al-Sadiq was celebrated among his brothers and peers and stood out among them for his great personal merits. He is highly respected by both Sunni and Shi'a Muslims for his great Islamic scholarship, pious character, and academic contributions.

Although he is perhaps most famous as the founder of Shi'a Islamic fiqh, known as Ja'fari jurisprudence, he had many other accomplishments. He was the teacher of many subsequent Muslim scholars such as the founders of both Sunni and Shi'a Islamic schools of jurisprudence. As well as being considered an Imam of the Shi'a, he is revered by the Naqshbandi Sunni Sufi chain.He was a polymath: an astronomer, alchemist, Imam, Islamic scholar, Islamic theologian, writer, philosopher, physician, physicist and scientist. He was also the teacher of the famous chemist, Jābir ibn Hayyān (Geber),  and a contemporary of Abū Ḥanīfa, the founder of the Hanafi school of Sunni Islamic jurisprudence.

Anecdotes

Someone once asked Ja'far Al-Sadiq to show him God. Ja'far Al-Sadiq replied, "Look at the sun." The man replied that he could not look at the sun because it was too bright.

Ja'far Al-Sadiq replied: "If you cannot see the created, how can you expect to see the creator?"

Khalid ibn Yazid

In alchemy, Calid often refers to a historical figure, Khalid ibn Yazid (died 704CE). He was an Umayyad prince, a brother of Muawiyah who was briefly caliph. Prince Khalid lost the chance of inheriting the title, but took an interest in the study of alchemy, in Egypt. A book collector , he facilitated translations into Arabic of the existing literature. It is to this Khalid that later allusions to Calid rex (King Calid) refer.

It is contested whether the attributions to Khalid ibn Yazid of alchemical writing are justified. A popular legend has him consulting a Byzantine monk Marianos (Morienus the Greek).The Liber de compositione alchimiae, which was the first alchemical work translated from Arabic to Latin (by Robert of Chester in 1144) was purportedly an epistle of Marianos to Khalid.

Another traditional attribution is of the Liber Trium Verborum. Forms as Calid filius Ysidri attempt to distinguish ibn Yazid from others named Calid. Calid filius Hahmil certainly intends ibn Umail. There is a Calid filius Jaici mentioned by Jean-Jacques Manget, who includes an attributed Liber Secretorum Artis in his 1702 compilation Bibliotheca Curiosa Chemica.