Taqi ad-Din Muhammad ibn Ma'ruf
Work in the observatorium of Taqi ad-Din
|Fields||Mathematics, astronomy, engineering, mechanics, optics, natural philosophy|
|Known for||Istanbul observatory|
Taqi ad-Din Muhammad ibn Ma'ruf ash-Shami al-Asadi (Arabic: تقي الدين محمد بن معروف الشامي, Modern Turkish: Takiyuddin or Taki) (1526–1585) was an Ottoman Turkish or Syrian Muslim polymath: He was the author of more than ninety books on a wide variety of subjects, including astronomy, clocks, engineering, mathematics, mechanics, optics and natural philosophy. In 1574 the Ottoman Sultan Murād III invited Taqī ad-Dīn to build the Istanbul observatory. Using his exceptional knowledge in the mechanical arts, Taqī ad-Dīn constructed instruments like huge armillary and mechanical clocks that he used in his observations of the Great Comet of 1577. He also used European celestial and terrestrial globes that were delivered to Istanbul in gift-exchange. The major work that resulted his work in the observatory is titled The tree of ultimate knowledge [in the end of time or the world] in the Kingdom of the Revolving Spheres: The astronomical tables of the King of Kings [Murād III](Sidrat al-muntah al-afkar fi malkūt al-falak al-dawār– al-zij al-Shāhinshāhi). The work was prepared according to the results of the observations carried out in Egypt and Istanbul in order to correct and complete Ulugh Beg’s Zij as-Sultani. The first 40 pages of the work deal with calculations, followed by discussions of astronomical clocks, heavenly circles, and information about three eclipses which he observed at Cairo and Istanbul. For corroborating data of other observations of eclipses in other locale like Daud ar-Riyyadi (David the Mathematician), David Ben-Shushan of Salonika. According to the Habsburg ambassador, Salomon Schweigger, Taqi ad-Din was a charlatan who deceived Sultan Murad III and had him spent enormous resources.
Taqi ad-Din's method of finding coordinates of stars was reportedly more precise than those of his contemporaries, Tycho Brahe and Nicolas Copernicus. Brahe is thought to have been aware of Taqi ad-Din's work.
The Istanbul Observatory
In 1574 Taqi ad-Din proposed the new observatory to Sultan Murad III who, having an interest in astronomy, provided the financing for a new observatory to be built in Istanbul. He used errors in various astronomical tables as reasoning for the new project. His observatory, it is said, resembles Tyco’s in many respects. A few months after opening, on the first day of Ramadan, a comet appeared in the night sky. This was unfortunate timing as the current Sultan was about to march on Persia and his fathers death had been heralded by a comet. It sat in the night sky for 40 nights growing slowly brighter. With this in mind he asked Taqi to use the observatory to figure out what the meaning of the apparition. Taqi noted that both the head and tail of the comet seemed to be pointing in the direction on Persia indicating that it was more of a bad omen for them and not for the Ottoman Empire. He also noted that the comet appeared in Sagittarius, which represented an Ottoman archer, and would set in Aquarius, which represented a time of peace. He strongly believed that this comet was a good sign for the Sultan and the Ottoman Empire in their march against Persia. While their armies did do well a plague broke out at roughly the same time. This caused political pressure against continued funding of the observatory. Grand Vizier Sokullu pushed for continued funding until his death in 1580. Without political protection, the observatory was torn down shortly after.
Taqī al-Dīn, being an astronomer, was very familiar with optics and the behavior of light. From this he wrote a book called Takîyüddîn'in Optik Kitabi or Taqī al-Dīn's Book of Optics. This book is written in three chapters. The first deals with the nature of vision, the second with reflection and then concludes with an understanding of refraction. He makes special note that his book is based on experimental evidence rather than being a conclusion drawn of previous works of literature. He also makes note that light is the same from all sources, contradicting Ibn al-Haytham.
In the early Greek world there were two competing ideas of sight. One that rays emanated from the eyes onto an object and another that and object emanated light and our eyes only observed it. Both sides has their champions however Taqī al-Dīn was able to show experimentally that light emanates from an object and is then collected by our eyes. “According to him, if the ray of light had emerged from the eye, it would take too much time for us to see in the sphere of fixed stars.”  Since we can see the stars at night without any delay it is clear that light comes from them and not something we produce. From this he also argued that the color of the light is thus contained within the light of the object. He also argued that while light, emanating from a single point, may travel outward in a sphere the individual rays of light travel in straight lines. Finally he showed that the color of an object was produced by the reflection and refraction properties of an object.
Reflection itself was nothing new to the Islamic world and had been figured out for quite some time. However, any optics book that left out a section of reflective surfaces would be strikingly lacking. To this effect a section was included. He noted that rays of light being reflected off a mirror will propagate is a spherical form. As such, reflections of rays are a geometrical problem. It had been found that the incident ray, the reflected ray and the normal all lie in the same plane. It was also discovered that the angle of incidence and the angle of reflection were the same. The rays of light being emitted will also have the same color as the reflective surface.
Like reflection, refraction had been known about for some time. It was, however, a much more complicated problem that required further work. It was known that that refracted light propagates in a spherical shell much as reflected light does and that it also takes on the color of the material through which it is traveling. It was also known that if a ray of light is traveling and goes from one medium to another that its angle will bend in a manor related to the density of the two materials. Like reflections the incident ray, the refracted ray and the normal all lie in the same place however the angle of refraction is always less than the angle of incidence. The only exceptions to this are perpendicular rays which do not in fact refract. Taqī al-Dīn did discover though that “the difference between the refraction angles of different incident rays is less than the difference between the angles of incidence.” He also noted that “the ratio of the angle of the larger incident to its refraction angle is larger than the ratio of the angle of the smaller incident to its refraction angle.”  These are pretty much still our modern rules for optics and Taqī al-Dīn even tried to formulate Snell’s law although he was unsuccessful. 
- Islamic science
- Islamic astronomy
- Istanbul observatory of Taqi ad-Din
- Inventions in the Muslim world
- " Chief Astronomer Taqi al-Din was born to a family of Turkish descent in Damascus." Hoffmann, Dieter; İhsanoğlu, Ekmeleddin; Djebbar, Ahmed; Günergun, Feza. Science, technology, and industry in the Ottoman world in Volume 6 of Proceedings of the XXth International Congress of History of Science p. 19. Publisher Brepols, 2000. ISBN 2-503-51095-7
- Ágoston, Gábor; Masters, Bruce Alan. Encyclopedia of the Ottoman Empire Infobase Publishing, 2009. p. 552 ISBN 0-8160-6259-5
- Ibn Haytham, Nader el-Bizri, Medieval Science Technology and Medicine: An Encyclopedia, ed. Thomas F. Glick, Steven Livesey, Faith Wallis, (Taylor & Francis Group, 2005), 239;"..composed as a commentary on Kamal al-Din's "Tanqih" by Taqi al-Din Muhammad ibn Ma'ruf, the Syrian astronomer at the Ottoman court".
- Salomon Schweigger, Ein newe Reyssbeschreibung auss Teutschland nach Constantinopel und Jerusalem (Graz, 1964), 90–1.
- "Arabs and Astronomy". Saudi Aramco World. Retrieved 6/3/2014.
- Ben-Zaken, Avner. "The Revolving Planets and the Revolving Clocks: Circulating Mechanical Objects in the Mediterranean", History of Science, xlix (2010), pp. 125-148.
- Ben-Zaken, Avner. Cross-Cultural Scientific Exchanges in the Eastern Mediterranean 1560-1660 (Johns Hopkins University Press, 2010), pp. 8-47.
- King, David A. "Taki al-Din". Encyclopaedia of Islam (2nd Ed.) 10: pp. 132–3.
- King, David A. (1986). A Survey of the Scientific manuscripts in the Egyptian National Library 5. Winona Lake, IN, USA: American Research Center in Egypt. pp. 171–2.
- Hassan, Ahmad Y (1976). Taqi al-Din and Arabic Mechanical Engineering. Institute for the History of Arabic Science, Aleppo University.
- Gautier, Antoine (December 2005). "L'âge d'or de l'astronomie ottomane". L'Astronomie 119.
- Tekeli, Sevim. (2002). 16’ıncı yüzyılda Osmanlılarda saat ve Takiyüddin’in “mekanik saat konstrüksüyonuna dair en parlak yıldızlar = The clocks in Ottoman Empire in 16th century and Taqi al Din’s the brightest stars for the construction of the mechanical clocks. Second edition, Ankara: T. C. Kültür Bakanlıgi.
- Unat, Yavuz, “Time in The Sky of Istanbul, Taqî al Dîn al-Râsid’s Observatory”, Art and Culture Magazine, Time in Art, Winter 2004/Issue 11, pp. 86–103.
- Fazlıoğlu, İhsan (2007). "Taqī al‐Dīn Abū Bakr Muḥammad ibn Zayn al‐Dīn Maʿrūf al‐Dimashqī al‐Ḥanafī". In Thomas Hockey et al. The Biographical Encyclopedia of Astronomers. New York: Springer. pp. 1122–3. ISBN 978-0-387-31022-0. (PDF version)