{{short description|Byzantine Greek astronomer}} {{Expand French|topic=bio|date=March 2025}} '''Gregory Chioniades''' ({{langx|el|Γρηγόριος Χιονιάδης|Grēgorios Chioniadēs}}; c. 1240 – c. 1320{{sfn|Haramundanis|2007|p=229}}) was a Byzantine Greek astronomer. He traveled to Persia, where he learned Persian mathematical and astronomical science, which he introduced into Byzantium upon his return from Persia<ref>Nicholas J. Moutafakis, ''Byzantine Philosophy'', Hackett Publishing, 2003, {{ISBN|0-87220-563-0}}, p. 200</ref> and founded an astronomical academy at Trebizond.{{sfn|Zehiroğlu|2016|pp=2-5}} Chioniades also served as Orthodox bishop in Tabriz.

==Biography== Information about Chioniades survives from some contemporary sources. In 1347, George Chrysokokkes wrote that {{cquote|a certain Chioniades, who had been raised in Constantinople, fell in love with mathematics and other sciences. After he had mastered medicine, he wished to study astronomy; he was informed that in order to satisfy his desire, he would have to go to Persia (then under Ilkhanate rule). He traveled to Trebizond, where he was given some assistance by the Emperor Alexios II of Trebizond, and thence proceeded to Persia itself, where he persuaded yet another Emperor to aid him. He eventually learned all that he wished to know, and returned to Trebizond, bearing away from Persia a number of astronomical texts which he translated into Greek.{{sfn|Pingree|1964|p=141}}}}

thumb| Epistolae of Gregory Chioniades, Athens 1902 edition by Trifon E. Evaggelides He was born in Constantinople, probably around 1240, and was originally named George.{{sfn|Haramundanis|2007|p=229}} Sixteen of Chioniades' letters have survived, which confirm that he received assistance from Alexios II and traveled to Persia. Chioniades translated a number of Arabic and Persian works on mathematics and astronomy, including the astronomical tables of his teacher Shams al-Din al-Bukhari,<ref>{{cite web|author=Thomas Hockey at al|title=Biographical Encyclopedia of astronomers|url=http://islamsci.mcgill.ca/RASI/BEA/Shams_al-Din_al-Bukhari_BEA.htm}}</ref> who had worked at the famous Maragheh observatory under the polymath Nasir al-Din al-Tusi. Chioniades played an important role in transmitting several innovations from the Islamic world to Europe. These include the introduction of the universal latitude-independent astrolabe to Europe and a Greek description of the Tusi couple, which would later have an influence on Copernican heliocentrism. Chioniades also translated several ''Zij'' treatises into Greek, including the Persian ''Zij-i Ilkhani'' by al-Tusi and the Maragheh observatory{{sfn|Leichter|2004}} as well as the Seljuk ''Sanjaric Tables'' by al-Khazini, an Islamic astronomer of Byzantine Greek descent.{{sfn|Pingree|1964|p=}}

Chioniades resided in Tabriz, at the time the Mongol capital, from 1295 to 1296, serving as the Orthodox bishop to the Orthodox community in that city, and later returned to Constantinople.{{sfn|Pingree|1964|p=141}} In 1302 he returned to Tabriz as bishop. According to David Pingree, this may have been in connection with Andronikos II Palaiologos's attempt to form an alliance with Ghazan Khan in the summer of 1302.

He stayed at Tabriz at least until 1310, before returning to Trebizond, where he is attested as a hieromonk around 1315.{{sfn|PLP|loc=30814. Χιονιάδης Γρηγόριος}} Chioniades also wrote religious works, including a commentary on John of Damascus, a liturgy {{Transliteration|el|akolouthia}} on St. Eugenios of Trebizond, and a profession of faith.{{sfn|PLP|loc=30814. Χιονιάδης Γρηγόριος}}

==Notes== {{reflist|2}}

==Sources== * Fryde, Edmund Boleslaw "The Early Palaeologan Renaissance 1261 - C. 1360" 2000 * {{cite encyclopedia | editor = Thomas Hockey | display-editors = etal | last = Haramundanis | first = Katherine | title=Chioniades, Gregor &#91;George&#93; | encyclopedia = The Biographical Encyclopedia of Astronomers | publisher = Springer | year = 2007 | location = New York | page = 229 | url=http://islamsci.mcgill.ca/RASI/BEA/Chioniades_BEA.htm | isbn=978-0-387-31022-0}} * {{cite thesis | last = Leichter | first = Joseph Gerard | url = https://archive.org/details/TheZijAs-sanjariOfGregoryChioniades | title = The Zīj as-Sanjarī of Gregory Chioniades: Text, Translation and Greek to Arabic Glossary | type =PhD thesis | year = 2004 | location = Providence, Rhode Island}} * {{cite journal | last = Pingree | first = David | author-link = David Pingree| year = 1964 | title = Gregory Chioniades and Palaeologan Astronomy | journal = Dumbarton Oaks Papers | volume = 18 | pages = 133–160 | doi = 10.2307/1291210 | jstor = 1291210 | doi-access = free }} * {{Prosopographisches Lexikon der Palaiologenzeit}} * {{cite journal | last = Westerink | first = L. G. | title = La profession de foi de Grégoire Chioniadès | journal = Revue des études byzantines | volume = 38 | year = 1980 | pages = 233–245 | doi = 10.3406/rebyz.1980.2109 | url = http://www.persee.fr/web/revues/home/prescript/article/rebyz_0766-5598_1980_num_38_1_2109 | language = French }} * {{cite web | last = Zehiroğlu | first = Ahmet M. | url = https://www.academia.edu/29570856 | title = Astronomy in the Trebizond Empire | year = 2016 | translator = Paula Darwish}}

==External links== * [https://wilbourhall.org/index.html#chioniades Gregory Chioniades' translation of the Zīj as-Sanjarī] by Al-Khazini, including an English translation, at wilbourhall.org . (Direct [https://archive.org/details/TheZijAs-sanjariOfGregoryChioniades archive.org link].)

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