Astronomy in the medieval Islamic world
Islamic astronomy comprises the astronomical developments made in the Islamic world during the Islamic Golden Age, written in the Arabic language. These developments took place in the Middle East, Central Asia, Al-Andalus, North Africa, in the Far East and India, it parallels the genesis of other Islamic sciences in its assimilation of foreign material and the amalgamation of the disparate elements of that material to create a science with Islamic characteristics. These included Greek and Indian works in particular, which were translated and built upon. Islamic astronomy played a significant role in the revival of Byzantine and European astronomy following the loss of knowledge during the early medieval period, notably with the production of Latin translations of Arabic works during the 12th century. Islamic astronomy had an influence on Chinese astronomy and Malian astronomy. A significant number of stars in the sky, such as Aldebaran and Deneb, astronomical terms such as alidade and nadir, are still referred to by their Arabic names.
A large corpus of literature from Islamic astronomy remains today, numbering 10,000 manuscripts scattered throughout the world, many of which have not been read or catalogued. So, a reasonably accurate picture of Islamic activity in the field of astronomy can be reconstructed. Ahmad Dallal notes that, unlike the Babylonians and Indians, who had developed elaborate systems of mathematical astronomical study, the pre-Islamic Arabs relied on empirical observations; these observations were based on the rising and setting of particular stars, this area of astronomical study was known as anwa. Anwa continued to be developed after Islamization by the Arabs, where Islamic astronomers added mathematical methods to their empirical observations. According to David King, after the rise of Islam, the religious obligation to determine the qibla and prayer times inspired more progress in astronomy for centuries. Donald Hill divided Islamic Astronomy into the four following distinct time periods in its history: Following the Islamic conquests, under the early caliphate, Muslim scholars began to absorb Hellenistic and Indian astronomical knowledge via translations into Arabic.
The first astronomical texts that were translated into Arabic were of Persian origin. The most notable of the texts was Zij al-Sindhind, an 8th-century Indian astronomical work, translated by Muhammad ibn Ibrahim al-Fazari and Yaqub ibn Tariq after 770 CE with the assistance of Indian astronomers who visited the court of caliph Al-Mansur in 770. Another text translated was the Zij al-Shah, a collection of astronomical tables compiled in Sasanid Persia over two centuries. Fragments of texts during this period indicate that Arabs adopted the sine function in place of the chords of arc used in Greek trigonometry; the House of Wisdom was an academy established in Baghdad under Abbasid caliph Al-Ma'mun in the early 9th century. From this time, independent investigation into the Ptolemaic system became possible. According to Dallal, the use of parameters and calculation methods from different scientific traditions made the Ptolemaic tradition "receptive right from the beginning to the possibility of observational refinement and mathematical restructuring".
Astronomical research was supported by the Abbasid caliph al-Mamun through The House of Wisdom. Baghdad and Damascus became the centers of such activity; the caliphs not only endowed the work with formal prestige. The first major Muslim work of astronomy was Zij al-Sindh by al-Khwarizmi in 830; the work contains tables for the movements of the Sun, the Moon and the five planets known at the time. The work is significant; this work marks the turning point in Islamic astronomy. Hitherto, Muslim astronomers had adopted a research approach to the field, translating works of others and learning discovered knowledge. Al-Khwarizmi's work marked the beginning of nontraditional methods of study and calculations. In 850, al-Farghani wrote Kitab fi Jawani; the book gave a summary of Ptolemic cosmography. However, it corrected Ptolemy based on findings of earlier Arab astronomers. Al-Farghani gave revised values for the obliquity of the ecliptic, the precessional movement of the apogees of the Sun and the Moon, the circumference of the Earth.
The book was circulated through the Muslim world, translated into Latin. In addition to Alfraganus's findings, Egyptian Astronomer Ibn Yunus was the first Astronomer to find valid fault in Ptolemy's calculations about the planet's movements and their peculiarity in the late 10th century. Ptolemy calculated that Earth's wobble, otherwise known as precession, varied 1 degree every 100 years. Ibn Yunus contradicted this finding by calculating; this was impossible to believe, since it was still thought that the Earth was the center of the universe. Ibn Yunus and Ibn al-Shatir's findings were part of Copernicus's calculations to figure out that the Sun was the center of the universe; the period when a distinctive Islamic system of astronomy flourished. The period began as the Muslim astronomers began questioning the framework of the Ptolemaic system of astronomy; these criticisms, remained within the geocentric framework and followed Ptolemy's astronomical paradigm.
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, moons and galaxies – in either observational or theoretical astronomy. Examples of topics or fields astronomers study include planetary science, solar astronomy, the origin or evolution of stars, or the formation of galaxies. Related but distinct subjects like physical cosmology. Astronomers fall under either of two main types: observational and theoretical. Observational astronomers analyze the data. In contrast, theoretical astronomers create and investigate models of things that cannot be observed; because it takes millions to billions of years for a system of stars or a galaxy to complete a life cycle, astronomers must observe snapshots of different systems at unique points in their evolution to determine how they form and die. They use these data to create models or simulations to theorize how different celestial objects work.
Further subcategories under these two main branches of astronomy include planetary astronomy, galactic astronomy, or physical cosmology. Astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using physical laws. Today, that distinction has disappeared and the terms "astronomer" and "astrophysicist" are interchangeable. Professional astronomers are educated individuals who have a Ph. D. in physics or astronomy and are employed by research institutions or universities. They spend the majority of their time working on research, although they quite have other duties such as teaching, building instruments, or aiding in the operation of an observatory; the number of professional astronomers in the United States is quite small. The American Astronomical Society, the major organization of professional astronomers in North America, has 7,000 members; this number includes scientists from other fields such as physics and engineering, whose research interests are related to astronomy.
The International Astronomical Union comprises 10,145 members from 70 different countries who are involved in astronomical research at the Ph. D. beyond. Contrary to the classical image of an old astronomer peering through a telescope through the dark hours of the night, it is far more common to use a charge-coupled device camera to record a long, deep exposure, allowing a more sensitive image to be created because the light is added over time. Before CCDs, photographic plates were a common method of observation. Modern astronomers spend little time at telescopes just a few weeks per year. Analysis of observed phenomena, along with making predictions as to the causes of what they observe, takes the majority of observational astronomers' time. Astronomers who serve as faculty spend much of their time teaching undergraduate and graduate classes. Most universities have outreach programs including public telescope time and sometimes planetariums as a public service to encourage interest in the field.
Those who become astronomers have a broad background in maths and computing in high school. Taking courses that teach how to research and present papers are invaluable. In college/university most astronomers get a Ph. D. in astronomy or physics. While there is a low number of professional astronomers, the field is popular among amateurs. Most cities have amateur astronomy clubs that meet on a regular basis and host star parties; the Astronomical Society of the Pacific is the largest general astronomical society in the world, comprising both professional and amateur astronomers as well as educators from 70 different nations. Like any hobby, most people who think of themselves as amateur astronomers may devote a few hours a month to stargazing and reading the latest developments in research. However, amateurs span the range from so-called "armchair astronomers" to the ambitious, who own science-grade telescopes and instruments with which they are able to make their own discoveries and assist professional astronomers in research.
List of astronomers List of women astronomers List of Muslim astronomers List of French astronomers List of Hungarian astronomers List of Russian astronomers and astrophysicists List of Slovenian astronomers Dallal, Ahmad. "Science and Technology". In Esposito, John; the Oxford History of Islam. Oxford University Press, New York. ISBN 0-300-15911-0. Kennedy, E. S.. "A Survey of Islamic Astronomical Tables. 46. Philadelphia: American Philosophical Society. Toomer, Gerald. "Al-Khwārizmī, Abu Jaʿfar Muḥammad ibn Mūsā". In Gillispie, Charles Coulston. Dictionary of Scientific Biography. 7. New York: Charles Scribner's Sons. ISBN 0-684-16962-2. American Astronomical Society European Astronomical Society International Astronomical Union Astronomical Society of the Pacific Space's astronomy news
Astrology in medieval Islam
The medieval Muslims took a keen interest in the study of astrology: because they considered the celestial bodies to be essential because the dwellers of desert-regions travelled at night, relied upon knowledge of the constellations for guidance in their journeys. After the advent of Islam, the Muslims needed to determine the time of the prayers, the direction of the Kaaba, the correct orientation of the mosque, all of which helped give a religious impetus to the study of astronomy and contributed towards the belief that the heavenly bodies were influential upon terrestrial affairs as well as the human condition; the science dealing with such influences was termed astrology, a discipline contained within the field of astronomy. The principles of these studies were rooted in Arabian, Babylonian and Indian traditions and both were developed by the Arabs following their establishment of a magnificent observatory and library of astronomical and astrological texts at Baghdad in the 8th century.
Throughout the medieval period the practical application of astrology was subject to deep philosophical debate by Muslim religious scholars and scientists. Astrological prognostications required a fair amount of exact scientific expertise and the quest for such knowledge within this era helped to provide the incentive for the study and development of astronomy. Medieval Islamic astrology and astronomy continued Hellenistic and Roman era traditions based on Ptolemy's Almagest. Centres of learning in medicine and astronomy/astrology were set up in Baghdad and Damascus, the Caliph Al-Mansur of Baghdad established a major observatory and library in the city, making it the world's astronomical centre. During this time knowledge of astronomy was increased, the astrolabe was invented by Al Fazari. Many modern star names are derived from their Persian names. Albumasur or Abu Ma'shar was one of the most influential Islamic astrologers, his treatise Introductorium in Astronomiam spoke of how'"only by observing the great diversity of planetary motions can we comprehend the unnumbered varieties of change in this world".
The Introductorium was one of the first books to find its way in translation through Spain and into Europe in the Middle Ages, was influential in the revival of astrology and astronomy there. Persians combined the disciplines of medicine and astrology by linking the curative properties of herbs with specific zodiac signs and planets. Mars, for instance, was considered hot and dry and so ruled plants with a hot or pungent taste, like hellebore, tobacco or mustard; these beliefs were adopted by European herbalists like Culpeper right up until the development of modern medicine. The Persians developed a system, by which the difference between the ascendant and each planet of the zodiac was calculated; this new position became a'part' of some kind. For example, the'part of fortune' is found by taking the difference between the sun and the ascendant and adding it to the moon. If the'part' thus calculated was in the 10th House in Libra, for instance, it suggested that money could be made from some kind of partnership.
The calendar introduced by Omar Khayyám Neyshabouri, based on the classical zodiac, remains in effect in Afghanistan and Iran as the official Persian calendar. The Almagest, together with the original contributions of 9th to 10th century Persian astronomy such as the astrolabe, was introduced to Christian Europe beginning in the 11th century, by contact with Islamic Spain. Another notable Persian astrologer and astronomer was Qutb al-Din al Shirazi born in Shiraz, he wrote critiques of Ptolemy's Almagest and produced two prominent works on astronomy:'The Limit of Accomplishment Concerning Knowledge of the Heavens' in 1281 and'The Royal Present' in 1284, both of which commented upon and improved on Ptolemy's work in the field of planetary motion. Al-Shirazi was the first person to give the correct scientific explanation for the formation of a rainbow. Ulugh Beyg was a fifteenth-century Timurid Sultan and a mathematician and astronomer, he built an observatory in 1428 and produced the first original star map since Ptolemy, which corrected the position of many stars and included many new ones.
Some of the principles of astrology were refuted by several medieval Islamic astronomers such as Al-Farabi, Ibn al-Haytham, Abu Rayhan al-Biruni and Averroes. Their reasons for refuting astrology were due to both scientific and religious reasons; however these refutations concerned the judicial branches of astrology rather than the natural principles of it. For example, Avicenna's refutation of astrology revealed support for its overarching principles, he stated that it was true that each planet had some influence on the earth, but his argument was the difficulty of astrologers being able to determine the exact effect of it. In essence, Avicenna did not refute astrology, but denied man’s limited capacity to be able to know the precise effects of the stars on the sublunar matter. With that, he did not refute the essential dogma of astrology, but only refuted our ability to understand it. Another Damascene scientist Ibn Qayyim Al-Jawziyya, in his Miftah Dar al-Sa'adah, used empirical arguments in astronomy in order to refute the judicial practice of astrology, most aligned to divination
Muhammad ibn Musa al-Khwarizmi
Muḥammad ibn Mūsā al-Khwārizmī Latinized as Algorithmi, was a Persian scholar who produced works in mathematics and geography under the patronage of the Caliph Al-Ma'mun of the Abbasid Caliphate. Around 820 AD he was appointed as the astronomer and head of the library of the House of Wisdom in Baghdad. Al-Khwarizmi's popularizing treatise on algebra presented the first systematic solution of linear and quadratic equations. One of his principal achievements in algebra was his demonstration of how to solve quadratic equations by completing the square, for which he provided geometric justifications; because he was the first to treat algebra as an independent discipline and introduced the methods of "reduction" and "balancing", he has been described as the father or founder of algebra. The term algebra itself comes from the title of his book, his name gave rise to the terms algorithm. His name is the origin of guarismo and of algarismo, both meaning digit. In the 12th century, Latin translations of his textbook on arithmetic which codified the various Indian numerals, introduced the decimal positional number system to the Western world.
The Compendious Book on Calculation by Completion and Balancing, translated into Latin by Robert of Chester in 1145, was used until the sixteenth century as the principal mathematical text-book of European universities. In addition to his best-known works, he revised Ptolemy's Geography, listing the longitudes and latitudes of various cities and localities, he further produced a set of astronomical tables and wrote about calendaric works, as well as the astrolabe and the sundial. Few details of al-Khwārizmī's life are known with certainty, he was born into a Persian family and Ibn al-Nadim gives his birthplace as Khwarezm in Greater Khorasan. Muhammad ibn Jarir al-Tabari gives his name as Muḥammad ibn Musá al-Khwārizmiyy al-Majūsiyy al-Quṭrubbaliyy; the epithet al-Qutrubbulli could indicate he might instead have come from Qutrubbul, a viticulture district near Baghdad. However, Rashed suggests: There is no need to be an expert on the period or a philologist to see that al-Tabari's second citation should read "Muhammad ibn Mūsa al-Khwārizmī and al-Majūsi al-Qutrubbulli," and that there are two people between whom the letter wa has been omitted in an early copy.
This would not be worth mentioning if a series of errors concerning the personality of al-Khwārizmī even the origins of his knowledge, had not been made. G. J. Toomer... with naive confidence constructed an entire fantasy on the error which cannot be denied the merit of amusing the reader. Regarding al-Khwārizmī's religion, Toomer writes: Another epithet given to him by al-Ṭabarī, "al-Majūsī," would seem to indicate that he was an adherent of the old Zoroastrian religion; this would still have been possible at that time for a man of Iranian origin, but the pious preface to al-Khwārizmī's Algebra shows that he was an orthodox Muslim, so al-Ṭabarī's epithet could mean no more than that his forebears, he in his youth, had been Zoroastrians. Ibn al-Nadīm's Kitāb al-Fihrist includes a short biography on al-Khwārizmī together with a list of the books he wrote. Al-Khwārizmī accomplished most of his work in the period between 813 and 833. After the Muslim conquest of Persia, Baghdad became the centre of scientific studies and trade, many merchants and scientists from as far as China and India traveled to this city, as did al-Khwārizmī.
He worked in Baghdad as a scholar at the House of Wisdom established by Caliph al-Ma’mūn, where he studied the sciences and mathematics, which included the translation of Greek and Sanskrit scientific manuscripts. Douglas Morton Dunlop suggests that it may have been possible that Muḥammad ibn Mūsā al-Khwārizmī was in fact the same person as Muḥammad ibn Mūsā ibn Shākir, the eldest of the three Banū Mūsā. Al-Khwārizmī's contributions to mathematics, geography and cartography established the basis for innovation in algebra and trigonometry, his systematic approach to solving linear and quadratic equations led to algebra, a word derived from the title of his book on the subject, "The Compendious Book on Calculation by Completion and Balancing". On the Calculation with Hindu Numerals written about 820, was principally responsible for spreading the Hindu–Arabic numeral system throughout the Middle East and Europe, it was translated into Latin as Algoritmi de numero Indorum. Al-Khwārizmī, rendered as Algoritmi, led to the term "algorithm".
Some of his work was based on Persian and Babylonian astronomy, Indian numbers, Greek mathematics. Al-Khwārizmī corrected Ptolemy's data for Africa and the Middle East. Another major book was Kitab surat al-ard, presenting the coordinates of places based on those in the Geography of Ptolemy but with improved values for the Mediterranean Sea and Africa, he wrote on mechanical devices like the astrolabe and sundial. He assisted a project to determine the circumference of the Earth and in making a world map for al-Ma'mun, the caliph, overseeing 70 geographers. When, in the 12th century, his works spread to Europe through Latin translations, it had a profound impact on the advance of mathematics in
Mashallah ibn Athari
Mā Shā’ Allāh ibn Athari was an eighth-century Persian Jewish astrologer and mathematician. From Khorasan he lived in Basra during the reigns of al-Manṣūr and al-Ma’mūn, was among those who introduced astrology and astronomy to Baghdād in the late 8th and early 9th century; the bibliographer al-Nadim in his Fihrist, described him "as virtuous and in his time a leader in the science of jurisprudence, i.e. the science of judgments of the stars". He served as a court astrologer for the Abbasid caliphate, wrote numerous works on astrology in Arabic; some Latin translations survive. The Arabic phrase ma sha`a allah indicates a believer's acceptance of God's ordainment of good or ill fortune; the name Sha'a Allah is an Arabic rendering of Hebrew Sh'luh, which in is the name of the Messiah referenced in Genesis 49:10. Al-Nadim writes Mashallah's name'Mīshā', means "yithro", the Hebrew name Jethro, from yithrā. Latin translators called him many variants such as Messahala, Messala, Macelarma, etc; the crater Messala on the Moon is named after him.
As a young man he participated in the founding of Baghdad for Caliph al-Manṣūr in 762 by working with a group of astrologers led by Naubakht the Persian to pick an electional horoscope for the founding of the city and building of an observatory. Attributed the author of over twenty titles, predominantly on astrology, his authority was established over the centuries in the Middle East, in the West, when horoscopic astrology was transmitted to Europe from the 12th century, his writings include both what would be recognized as traditional horary astrology and an earlier type of astrology which casts consultation charts to divine the client's intention. The strong influence of Hermes Trismegistus and Dorotheus is evident in his work; the Big Book of Births. Multiple translations into medieval Latin, Byzantine Greek and Hebrew were made. One of his most popular works in the Middle Ages was a cosmological treatise This comprehensive account of the cosmos along Aristotelian lines, covers many topics important to early cosmology.
Postulating a ten-orb universe it strays from traditional cosmology. Mashallah illustrated his main ideas with comprehensible diagrams. Two versions of the manuscript were printed: a short version De scientia motus orbis, an expanded version De elementis et orbibus; the short version was translated by Gherardo Cremonese. Both were printed in 1504 and 1549, respectively; this work is abbreviated to De orbe. Mashallah's treatise on the astrolabe is the first known of its kind. Translated from Arabic into Latin; the exact source of Geoffrey Chaucer's Treatise on the Astrolabe in Middle English is undetermined but most of his ‘conclusions’ go back, directly or indirectly, to a Latin translation of Mashallah's work, called Compositio et Operatio Astrolabii. Chaucer's description of the instrument amplifies Mashallah’s, his indebtedness was recognised by John Selden in 1613 and established by Walter William Skeat. While Mark Harvey Liddell held that Chaucer drew on De Sphaera of John de Sacrobosco for the substantial part of his astronomical definitions and descriptions, the non-correspondence suggests his probable source was another compilation.
Skeat's Treatise of the Astrolabe includes a collotype MS facsimile of the Latin version of the second part of Mashallah’s work, which parallels Chaucer's. This is found in R. T. Gunther's, Chaucer and Messahala on Astrology. De elementis, its contents deal with the construction and usage of an astrolabe. In 1981, Paul Kunitzsch argued that the treatise on the astrolabe long attributed to Mashallah is in fact written by Ibn al-Saffar. On Conjunctions and People was an astrological world history based on conjunctions of Jupiter and Saturn. A few fragments are extant as quotations by the Christian astrologer Ibn Hibinta. Liber Messahallaede revoltione liber annorum mundi, a work on revolutions, De rebus eclipsium et de conjunctionibus planetarum in revolutionibus annorm mundi, a work on eclipses. Nativities under its Arabic title Kitab al -
Fannā Khusraw, better known by his laqab of ʿAḍud al-Dawla was an emir of the Buyid dynasty, ruling from 949 to 983, at his height of power ruling an empire stretching from Makran as far to Yemen and the shores of the Mediterranean Sea. He is regarded as the greatest monarch of the dynasty, by the end of his reign was the most powerful ruler in the Middle East; the son of Rukn al-Dawla, Fanna Khusraw was given the title of Adud al-Dawla by the Abbasid caliph in 948 when he was made emir of Fars after the death of his childless uncle Imad al-Dawla, after which Rukn al-Dawla became the senior emir of the Buyids. In 974 Adud al-Dawla was sent by his father to save his cousin Izz al-Dawla from a rebellion. After defeating the rebel forces, he claimed the emirate of Iraq for himself, forced his cousin to abdicate, his father, became angered by this decision and restored Izz al-Dawla. After the death of Adud al-Dawla's father, his cousin was defeated. Adud al-Dawla became afterwards the sole ruler of the Buyid dynasty and assumed the Persian title Shahanshah.
When Adud al-Dawla became emir of Iraq, the capital city, was suffering from violence and instability owing to sectarian conflict. In order to bring peace and stability to the city, he ordered the banning of public demonstrations and polemics. At the same time, he patronized a number of Shia scholars such as al-Mufid, sponsored the renovation of a number of important Shia shrines. In addition,'Adud al-Dawla is credited with sponsoring and patronizing other scientific projects during his time. An observatory was built by his orders in Isfahan. Al-Muqaddasi reports that he ordered the construction of a great dam between Shiraz and Estakhr in 960; the dam became known as Band-e Amir. Among his other major constructions was the digging of the Haffar channel, that joined the Karun river to the Shatt al-Arab river; the port of Khorramshahr was built at its joining point with the Shatt al-Arab. Fanna Khusraw was born in Isfahan on September 24, 936, he was the son of Rukn al-Dawla, the brother of Imad al-Dawla and Mu'izz al-Dawla.
According to Ibn Isfandiyar, Fanna Khusraw's mother was the daughter of the Daylamite Firuzanid nobleman al-Hasan ibn al-Fairuzan, the cousin of the prominent Daylamite military leader Makan ibn Kaki. In 948, Fanna Khusraw was chosen by his uncle Imad al-Dawla as his successor. Imad al-Dawla died in December 949, thus Fanna Khusraw became the new ruler of Fars. However, this appointment was not accepted by a group of Daylamite officers, who shortly rebelled against Fanna Khusraw. Rukn al-Dawla left for southern Iran to save his son, was joined by the vizier of Mu'izz al-Dawla for the same purpose. Together they put Fanna Khusraw on the throne in Shiraz. Fanna Khusraw requested the title of "Taj al-Dawla" from the Abbasid caliph. However, to Mu'izz al-Dawla, the title of "Taj" implied that Fanna Khusraw was the superior ruler of the Buyid Empire, provoking a reaction from him, making him decline Fanna Khusraw's request. A more suitable title was instead chosen. Adud al-Dawla was only thirteen when he was crowned as the ruler of Fars, was educated there by his tutor Abu'l-Fadl ibn al-'Amid.
After the death of Imad al-Dawla in 949, Adud al-Dawla's father Rukn al-Dawla, the most powerful of the Buyid rulers, claimed the title of senior emir, which Mu'izz al-Dawla and Adud al-Dawla recognized. In 955, a Daylamite military officer named. Adud al-Dawla marched towards the city and recaptured it from Muhammad ibn Makan. Another Daylamite military officer named Ruzbahan shortly rebelled against Mu'izz al-Dawla, while his brother Bullaka rebelled against Adud al-Dawla at Shiraz. Abu'l-Fadl ibn al-'Amid, managed to suppress the rebellion. In 966, Adud al-Dawla and Mu'izz al-Dawla made a campaign to impose Buyid rule in Oman. Mu'izz al-Dawla died in 967, was succeeded by his eldest son Izz al-Dawla as emir of Iraq; the same year, Adud al-Dawla aided the Ziyarid Bisutun in securing the Ziyarid throne from his brother Qabus. Adud al-Dawla and Bisutun made an alliance, Bisutun married a daughter of Adud al-Dawla, while he married a daughter of Bisutun. In 967, Adud al-Dawla took advantage of the quarrel between the Ilyasid ruler Muhammad ibn Ilyas and his son in Kerman to annex the province to his domain.
Mu'izz al-Dawla had attempted to conquer the province but was defeated by the Ilyasids. Adud al-Dawla conquered all of Kerman, appointed his son Shirdil Abu'l-Fawaris as the viceroy of the province, while a Daylamite officer named Kurkir ibn Justan was appointed as the chief captain of the army of Kerman. In the next year, Adud al-Dawla negotiated peace with the Saffarid ruler Khalaf ibn Ahmad, who agreed to recognize Buyid authority. In 969/970, the son of Muhammad ibn Ilyas, wanted to regain his kingdom of Kerman, invaded the region. Adud al-Dawla managed to defeat the army of Sulaiman and continued to expand his domains to the strait of Hormuz. During his campaign in southern Iran, many Iranian tribes converted to Islam and pledged allegiance to him. On August/September 971, Adud al-Dawla launched a punitive expedition against the Baloch tribes who had declared independence. Adud al-Dawla defeated them on January 8, 972, installed loyal landowners to control the region. Afterwards
Abu al-Wafa' Buzjani
Abū al-Wafāʾ, Muḥammad ibn Muḥammad ibn Yaḥyā ibn Ismāʿīl ibn al-ʿAbbās al-Būzjānī or Abū al-Wafā Būzhjānī was a Persian mathematician and astronomer who worked in Baghdad. He made important innovations in spherical trigonometry, his work on arithmetics for businessmen contains the first instance of using negative numbers in a medieval Islamic text, he is credited with compiling the tables of sines and tangents at 15' intervals. He introduced the secant and cosecant functions, as well studied the interrelations between the six trigonometric lines associated with an arc, his Almagest was read by medieval Arabic astronomers in the centuries after his death. He is known to have written several other books, he was born in Khorasan. At age 19, in 959 AD, he moved to Baghdad and remained there for the next forty years, died there in 998, he was a contemporary of the distinguished scientists Abū Sahl al-Qūhī and Al-Sijzi who were in Baghdad at the time and others like Abu Nasr ibn Iraq, Abu-Mahmud Khojandi, Kushyar ibn Labban and Al-Biruni.
In Baghdad, he received patronage by members of the Buyid court. Abu Al-Wafa' was the first to build a wall quadrant to observe the sky, it has been suggested that he was influenced by the works of Al-Battani as the latter describes a quadrant instrument in his Kitāb az-Zīj. His use of tangent helped to solve problems involving right-angled spherical triangles, developed a new technique to calculate sine tables, allowing him to construct more accurate tables than his predecessors. In 997, he participated in an experiment to determine the difference in local time between his location and that of al-Biruni; the result was close to present-day calculations, showing a difference of 1 hour between the two longitudes. Abu al-Wafa is known to have worked with Abū Sahl al-Qūhī, a famous maker of astronomical instruments. While what is extant from his works lacks theoretical innovation, his observational data were used by many astronomers, including al-Biruni. Among his works on astronomy, only the first seven treatises of his Almagest are now extant.
The work covers numerous topics in the fields of plane and spherical trigonometry, planetary theory, solutions to determine the direction of Qibla. He established several trigonometric identities such as sin in their modern form, where the Ancient Greek mathematicians had expressed the equivalent identities in terms of chords. Sin = sin α cos β ± cos α sin β sin = sin cos + cos sin cos = 1 − 2 sin 2 sin = 2 sin cos He discovered the law of sines for spherical triangles: sin A sin a = sin B sin b = sin C sin c where A, B, C are the sides and a, b, c are the opposing angles; some sources suggest that he introduced the tangent function, although other sources give the credit for this innovation to al-Marwazi. Almagest. A book of zij called Zīj al‐wāḍiḥ, no longer extant. "A Book on Those Geometric Constructions Which Are Necessary for a Craftsman". This text contains over one hundred geometric constructions, including for a regular heptagon, which have been reviewed and compared with other mathematical treatises.
The legacy of this text in Latin Europe is still debated. "A Book on What Is Necessary from the Science of Arithmetic for Scribes and Businessmen". This is the first book, he wrote translations and commentaries on the algebraic works of Diophantus, al-Khwārizmī, Euclid's Elements. The crater Abul Wáfa on the Moon is named after him. On June 2015 Google has changed its logo in memory of Abu al-Wafa' Buzjani. O'Connor, John J.. Hashemipour, Behnaz. "Būzjānī: Abū al‐Wafāʾ Muḥammad ibn Muḥammad ibn Yaḥyā al‐Būzjānī". In Thomas Hockey; the Biographical Encyclopedia of Astronomers. New York: Springer. Pp. 188–9. ISBN 978-0-387-3