Ala al-Dīn Ali ibn Muhammed (1403 – 16 December 1474), known as Ali Qushji (Ottoman Turkish/Persian language: علی قوشچی, kuşçu - falconer in Turkish;[1] Latin: Ali Kushgii) was an astronomer, mathematician and physicistoriginally from Samarkand, who settled in the Ottoman Empire some time before 1472.[2] As a disciple of Ulugh Beg, he is best known for the development of astronomical physics independent from natural philosophy, and for providing empirical evidence for the Earth's rotation in his treatise,Concerning the Supposed Dependence of Astronomy upon Philosophy. In addition to his contributions to Ulugh Beg's famous work Zij-i-Sultani and to the founding of Sahn-ı Seman Medrese, one of the first centers for the study of various traditional Islamic sciences in the Ottoman caliphate, Ali Kuşçu was also the author of several scientific works and textbooks on astronomy.[3]

Early life and works
Ali Kuşçu was born in 1403 in the city of Samarkand, in present-day Uzbekistan. His full name at birth was Ala al-Dīn Ali ibn Muhammed al-Qushji. The last name Qushji derived from the Turkish term kuşçu—"falconer"[1]—due to the fact that Ali's father Muhammad was the royal falconer of Ulugh Beg.[3] Sources consider him Turkic[4][5] or Persian.[6]

He attended the courses of Qazi zadeh Rumi, Ghiyāth al-Dīn Jamshīd Kāshānī andMuin al-Dīn Kashi. He moved to Kerman, Iran (Persia), where he conducted some research on storms in the Oman sea. He completed Hall-e Eshkal-i Ghammar(Explanations of the Periods of the Moon) and Sharh-e Tajrid in Kirman. He moved to Herat and taught Molla Cami about astronomy (1423). After professing in Herat for a while he went back to Samarkand There he presented his work on the Moon to Ulugh Beg, who found it so fascinating that he read the entire work while standing up. Ulugh Beg assigned him to Ulugh Beg Observatory, which was called Samarkand Observatory at that time. Qushji worked there until Ulugh Beg was assassinated.[7]

After Ulugh Beg's death, Ali Kuşçu went to Herat, Tashkent, and finally Tabrizwhere, around 1470, the Ak Koyunlu ruler Uzun Hasan sent him as a delegate to the Ottoman Sultan Mehmed II. At that timeHusayn Bayqarah had come to reign in Herat but Qushji preferred Constantinople over Herat because of Sultan Mehmed's attitude toward scientists and intellectuals.

Constantinople era
When he came to Constantinople (present-day Istanbul), his grandson Ghutb al-Dīn Muhammed had a son Mirim Çelebi who would be a great mathematician and astronomer in the future.[8] Ali Kuşçu composed "risalah dar hay’at" in Persian forMehmed II at Constantinople in 1470.[9] Also he wrote "Sharh e resalye Fathiyeh",[10] "resalye Mohammadiye" in Constantinople, which are in Arabic on the topic of mathematics. He then finished "Sharh e tejrid" on Nasir al-Din al-Tusi's "Tejrid al-kalam". That work is called "Sharh e Jadid" in scientific community.

Contributions to astronomy
Qushji improved on Nasir al-Din al-Tusi's planetary model and presented an alternative planetary model for Mercury.[11] He was also one of the astronomers that were part of Ulugh Beg's team of researchers working at the Samarqand observatoryand contributed towards the Zij-i-Sultani compiled there. In addition to his contributions to Zij, Ali Kuşçu wrote nine works in astronomy, two of them in Persian and seven in Arabic.[3] A Latin translation of two of Qushji's works, the Tract on Arithmeticand Tract on Astronomy, was published by John Greaves in 1650.
Concerning the Supposed Dependence of Astronomy upon Philosophy
Qushji's most important astronomical work is Concerning the Supposed Dependence of Astronomy upon Philosophy. Under the influence of Islamic theologians who opposed the interference of Aristotelianism in astronomy, Qushji rejected Aristotelian physics and completely separated natural philosophy from Islamic astronomy, allowing astronomy to become a purely empirical and mathematical science. This allowed him to explore alternatives to the Aristotelian notion of a stationary Earth, as he explored the idea of a moving Earth instead (though Savage-Smith asserts that no Islamic astronomers proposed a heliocentric universe[12]). He found empirical evidence for the Earth's rotation through his observation on comets and concluded, on the basis of empirical evidence rather than speculative philosophy, that the moving Earth theory is just as likely to be true as the stationary Earth theory.[13][14][15]

His predecessor al-Tusi had previously realized that "the monoformity of falling bodies, and the uniformity of celestial motions," both moved "in a single way,” though he still relied on Aristotelian physics to provide "certain principles that only the natural philosophers could provide the astronomer." Qushji took this concept further and proposed that "the astronomer had no need for Aristotelian physics and in fact should establish his own physical principles independently of the natural philosophers." Alongside his rejection of Aristotle's concept of a stationary Earth,[16] Qushji suggested that there was no need for astronomers to follow the Aristotelian notion of the heavenly bodies moving in uniform circular motion.[12]

Qushji's work was an important step away from Aristotelian physics and towards an independent astronomical physics.[17]This is considered to be a "conceptual revolution"[12][17] that had no precedent in European astronomy prior to theCopernican Revolution in the 16th century.[18] Qushji's view on the Earth's motion was similar to the later views of Nicolaus Copernicus on this issue, though it is uncertain whether the former had any influence on the latter. However, it is likely that they both may have arrived at similar conclusions due to using the earlier work of Nasir al-Din al-Tusi as a basis. This is more of a possibility considering "the remarkable coincidence between a passage in De revolutionibus (I.8) and one in Ṭūsī’sTadhkira (II.1[6]) in which Copernicus follows Ṭūsī’s objection to Ptolemy’s "proofs" of the Earth’s immobility."[19]
Astronomy
• Sharh e Zîj e Ulugh Beg (In Persian)
• Resale fi Halle Eshkale Moadeleye Ghamar lil-Masir (Faide fi Eshkâli Utared)
• Resale fi Asli'l-HâricYumkin fi's-Sufliyyeyn
• Sharh 'ale't-Tuhfeti'sh-Shâhiyye fi al-Heyat
• Resale dar elm-i Heyat (In Persian)
• el-Fathiyye fî elm al-Heyat (In Arabic)
• Resale fi Hall-e Eshkal-i Ghammar (In Persian)
• Concerning the Supposed Dependence of Astronomy upon Philosophy
Mathematics
• Resaletu'l-Muhammediyye fi-Hesab (In Persian)
• Resale dar elm-e Hesab: Suleymaniye
Kalam and Fiqh
• Sharh e Jadid ale't-Tejrîd
• Hashiye ale't-Telvîh
• Unkud-üz-Zevahir fi Nazm-al-Javaher
Mechanics
• Tazkare fi Âlâti'r-Ruhâniyye
Linguistics
• Sharh Risâleti'l-Vadiyye
• El-Ifsâh
• El-Unkûdu'z-Zevâhir fî Nazmi'l-Javâher
• Sharh e'Sh-Shâfiye
• Resale fî Beyâni Vadi'l-Mufredât
• Fâ'ide li-Tahkîki Lâmi't-Ta'rîf
• Resale mâ Ene Kultu
• Resale fî'l-Hamd
• Resale fî Ilmi'l-Me'ânî
• Resale fî Bahsi'l-Mufred
• Resale fî'l-Fenni's-Sânî min Ilmihal-Beyân
• Tafsir e-Bakara ve Âli Imrân
• Risâle fî'l-İstişâre
• Mahbub-al-Hamail fi kashf-al-mesail
• Tajrid-al-Kalam
Astronomy among Ottomans and Turks
SPOT 1: Ottoman astronomy owes much to the work carried out at the court of Ulug Bey in Herat in the 15th century. Ulug Bey was the grandson of Timur-i Leng and fervently interested in science and mathematics. At Herat, he gathered at his court some of the leading astronomers and mathematicians of the Islamic worldSPOT 2: The second Ottoman Imperial Observatory (Rasadhane-I Amire) was set up in 1868 in a han at Parmakkapı, Beyoğlu, where the Fitas-Dunya Cinema stands today; the director appointed was Aristede Coumnbary, who had come from France for the construction of the railway. The observatory as such compiled statistics on meteorological events, earthquakes and their effects.

As Muslims all over the world look to the skies this month to mark the beginning of the month of Ramadan and the end of their daily fast, they are participating in a relationship between Islam and astronomy that stretches back hundreds of years. Multiple requirements of Islam are related to the lunar calendar, including the start of this month's festival of Ramadan, as well as the times of prayer and the location of Mecca as the direction one faces when praying.
Modern astronomy is based on the discoveries and inventions of ancient China and their subsequent slow spread to the West. Astronomy was one of the very first sciences to develop as it only required gazing up at the night sky. Stars and planets were given human, animal or divine identities. The earliest of the Indian and Near Eastern civilizations also had their own astronomy, which may be more accurately called astrology. Then the Greeks and the Romans took over the science, as knowledge of the sun, moon and stars grew.

The most influential of the ancient astronomers was the astronomer and mathematician Ptolemy, who lived in Egypt in the second century A.D. and whose works had a profound influence on later Islamic and European science. His writings, discovered and translated in the ninth century, were used as a platform for discussion and conjecture.
Unlike in the West, there was little or no distinction between astronomy and astrology among Muslim scholars, and the stars were often used for fortune telling. For example, sometimes men at the Sultanahmet Mosque would be persuaded to look at the stars to select an auspicious day on which to get married. Others might cast star charts at the birth of an important person's son to predict his future.
Ottoman astronomy owes much to the work carried out at the court of Ulug Bey in Herat in the 15th century. Bey was the grandson of Timur-i Leng (known as Tamerlane in the West) and fervently interested in science and mathematics. At Herat, he gathered in his court some of the leading astronomers and mathematicians of the Islamic world.
The contributions that Bey made were outstanding for his time and place and served as another basis for future work by Islamic astronomers and mathematicians. He had a large observatory built where scholars could carry out their study of the heavens, and one of these learned men, Ali Kuşçu, was to move to Istanbul, where he taught at the schools that Fatih Sultan Mehmed had erected after his conquest of the city.

Astronomy among the Ottomans
According to professor Ekmeleddin Ihsanoğlu, 2,438 astronomical works were published by 582 Ottoman scholars over the course of the Ottoman Empire and similar figures are available for mathematicians.
Scholars often worked in both branches of science. One of these scholars was Ali Kuşçu, whose grandson, Mirim Çelebi, became a well-known mathematician.
Many of the astronomical works came from the mind of Takiyeddin ibn Manuf ar-Rasid, who lived from 1521 to 1585. Rasid originally came from Damascus and had the support of Ottoman Grand Vizier Sokullu Mehmet Pasa. He was commissioned to set up an observatory in 1575 and did so above Tophane on the highest hill close to the center of the city.

However, in 1577 a comet was seen in the skies and the following year the plague broke out in Istanbul. Rumors broke out in the city that Takiyeddin and his assistants had been observing the legs of the angels and the sultan and Murat III, was persuaded to order the destruction of the observatory in 1580. Admiral Kılıç Ali Paşa carried this out by firing cannonballs from the sea.
It is said the ruins extended down the hill, but today there is no trace of the observatory, although some believe that Takiyeddin rebuilt it later. The buildings would probably have been somewhere between modern day Galatasaray Lycee and Galata Tower.
Takiyeddin was far ahead his contemporaries and even of the mathematicians and astronomers who came after him. He wrote more than 1,300 works in Turkish, Arabic and Persian, a portion of which are kept at the Kandilli Observatory today. In trigonometry, he was more advanced than the 16th century astronomer Copernicus, and in arithmetic he developed a concept of fractions that would not be published in Europe for another 10 years. Takiyeddin was also interested in optics and as he had a practical bent, he designed clocks and mechanisms for drawing water from lakes, rivers and wells.
During the 17th century, Ottoman astronomy opened itself up to some Western influences. Translations of astronomical tables and some geographical books led to the introduction of European astronomy into the Ottoman Empire. Of particular importance was the translation of Latin works into Turkish for the first time, while Bey's astronomical tables were also made available for the first time in Turkish.
Ibrahim Muteferrika is mainly known for introducing the printing press for Ottoman Turkish works and for introducing European techniques. Much less widely known is the addendum he wrote to Katib Çelebi's geographic work, Cihannuma, in which he wrote about astronomy and geography.
The most important astronomer of the 18th century was Ramazan Salih Omer Hicazi Omer el-Haneki with 25 books on astronomical subjects to his credit. He based some of his works on Bey's astronomical tables.
Some writers were more prolific than others, often producing books that were astronomical tables and calculations designed to correct “mistakes” in earlier works.
The Observatory in modern times
The second Ottoman imperial observatory, Rasadhane-I Amire, was set up in 1868 in Beyoğlu, where the Fitaş-Dünya Cinema stands today; the director appointed was Aristede Coumnbary, who had come from France for the construction of the railway. The observatory compiled a collection of statistics on meteorological events, earthquakes and their effects and published a book on the 20 years of data collected from 1868 to 1887. It also calculated prayer times and eclipses and would relay every morning Istanbul's weather to Paris, Rome, Petersburg, Vienna, Odessa, Athens, Sofia and Belgrade.
After the proclamation of the Second Republic, the building and instruments were ruined during the upheaval that followed in 1909, and what could be salvaged was moved to Maçka. Two years later, Fatin Hoca (Gökmen) who had been in charge since 1910 re-established the observatory in Kandilli with the help of the French Meteorology Union and it is still there today.

In 1982 the observatory was turned over to Bosphorus University. The Kandilli Observatory has added the function of an earthquake research institute to its regular activities and there are astrophysics and solar physics, geomagnetism, seismology and meteorology laboratories as well as departments of earthquake engineering, geodesy and geophysics.

Since 1982, Kandilli has had six directors. The current director is professor Gülay Altay, but most people will remember the director between 1991 and 2002, professor Ahmet Mete Işıkara, who became something of a media hero in the aftermath of the Marmara earthquake of 1999. This year the Kandilli Observatory celebrates its 140th year with a series of events.
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