Editing Regiomontanus (section)

==Life==
[[File:Regiomontanus-Koenigsberg.JPG|thumb|left|Plaque at Regiomontanus' birthplace]]
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Although little is known of Regiomontanus' early life, it is believed that at eleven years of age, he became a student at the [[University of Leipzig]], [[Electorate of Saxony|Saxony]]. In 1451 he continued his studies at [[University of Vienna|Alma Mater Rudolfina]], the university in [[Vienna]], in the Duchy of Austria, where he became a pupil and friend of [[Georg von Peuerbach]]. In 1452 he was awarded his [[bachelor's degree]] (''baccalaureus''), and he was awarded his [[master's degree]] (''magister artium'') at the age of 21 in 1457.<ref name="NDB">{{NDB|21|270|271|Regiomontan(us) (eigentlich Müller, auch Francus, Germanus), Johannes |Folkerts, Menso; Kühne, Andreas |118641913}}</ref> He lectured in [[optics]] and ancient literature.<ref name="Catholic">{{Catholic |inline=1 |prescript= |wstitle=Johann Müller (Regiomontanus) |volume=10 |first=Johann Georg |last=Hagen }}</ref>

In 1460 the papal legate [[Basilios Bessarion]] came to Vienna on a diplomatic mission. Being a humanist scholar with a great interest in the mathematical sciences, Bessarion sought out Peuerbach's company. [[George of Trebizond]] who was Bessarion's philosophical rival had recently produced a new Latin translation of [[Ptolemy]]'s ''[[Almagest]]'' from the Greek, which Bessarion, correctly, regarded as inaccurate and badly translated, so he asked Peuerbach to produce a new one. Peuerbach's Greek was not good enough to do a translation but he knew the ''Almagest'' intimately so instead he started work on a modernised, improved abridgement of the work. Bessarion also invited Peuerbach to become part of his household and to accompany him back to Italy when his work in Vienna was finished. Peuerbach accepted the invitation on the condition that Regiomontanus could also accompany them. However Peuerbach fell ill in 1461 and died having completed only the first six books of his abridgement of the ''Almagest''. On his death bed Peuerbach made Regiomontanus promise to finish the book and publish it.<ref name="MacTutor">{{MacTutor Biography|id=Regiomontanus}}</ref><ref name="Catholic"/>

In 1461 Regiomontanus left Vienna with Bessarion and spent the next four years travelling around Northern Italy as a member of Bessarion's household, looking for and copying mathematical and astronomical manuscripts for Bessarion, who possessed the largest private library in Europe at the time. Regiomontanus also made the acquaintance of the leading Italian mathematicians of the age such as [[Giovanni Bianchini]] and [[Paolo dal Pozzo Toscanelli]] who had also been friends of Peuerbach during his prolonged stay in Italy more than twenty years earlier.<ref name="MacTutor"/>

In 1467, he went to work for [[János Vitéz (bishop)|János Vitéz]], archbishop of [[Esztergom]]. There he calculated extensive astronomical tables and built astronomical instruments.<ref name="NDB" /> Next he went to [[Buda]], and the court of [[Matthias Corvinus]] of Hungary, for whom he built an astrolabe, and where he collated Greek manuscripts for a handsome salary.<ref name=eb>{{Cite EB1911 |last=Clerke |first=Agnes Mary |author-link=Agnes Mary Clerke |wstitle=Regiomontanus}}</ref> The [[trigonometric tables]] that he created while living in Hungary, his ''Tabulae directionum profectionumque'' (printed [[Posthumous publication|posthum.]], 1490), were designed for astrology, including finding astrological houses.<ref>{{cite web |last=Mosley |first=Adam | url=http://www.hps.cam.ac.uk/starry/regioastrol.html | title=Regiomontanus and Astrology | publisher=Cambridge University: History and Philosophy of Science Department | date=1999 | access-date=12 June 2013 }}</ref> The ''Tabulae'' also contained several [[tangent tables]].<ref>Denis Roegel, [https://hal.inria.fr/inria-00543931/PDF/rheticus1551doc.pdf "A reconstruction of the tables of Rheticus' ''Canon doctrinæ triangulorum'' (1551)"], 2010.</ref>

In 1471 Regiomontanus moved to the Free City of [[Nuremberg]], in [[Franconia]], then one of the Empire's important seats of learning, publication, commerce and art, where he worked with the humanist and merchant [[Bernhard Walther]].<ref name="eb" /> Here he founded the world's first scientific printing press, and in 1472 he published the first printed astronomical textbook, the ''Theoricae novae Planetarum'' of his teacher Georg von Peurbach.<ref name="MacTutor" />

Regiomontanus and Bernhard Walther observed the [[comet of 1472]]. Regiomontanus tried to estimate its distance from Earth, using the angle of parallax.{{efn|See [http://www2.jpl.nasa.gov/teachers/attachments/parallax.html NASA: parallax].}} According to David A. Seargeant:<ref>David A. Seargeant. ''The Greatest Comets in History'', 2009, p. 104</ref>

{{Blockquote|In agreement with the prevailing Aristotelian theory on comets as atmospheric phenomena, he estimated its distance to be at least 8,200 miles (13,120 km) and, from this, estimated the central condensation as 26, and the entire coma as 81 miles (41.6 and 129.6 km respectively) in diameter. These values, of course, fail by orders of magnitude, but he is to be commended for this attempt at determining the physical dimensions of the comet.}}
The 1472 comet was visible from Christmas Day 1471 to 1 March 1472 (Julian Calendar), a total of 59 days.<ref>Donald K. Yeomans, ''[http://ssd.jpl.nasa.gov/?great_comets Jet Propulsion Laboratory: Great Comets in History]'', 2007.</ref>

In 1475, Regiomontanus was called to Rome by [[Pope Sixtus IV]] on to work on the planned [[Gregorian calendar#Background|calendar reform]]. Sixtus promised substantial rewards, including the title of [[bishop of Regensburg]],<ref>{{Cite book |url=https://books.google.com/books?id=antLAAAAcAAJ&pg=PA351 |title=Versuch einer allgemeinen Geschichte der Mathematik |last=Boffut |first=Carl |publisher=L. G. Hoffmann |year=1804 |pages=351 |language=de}}</ref><ref>Rudolf Schmidt,  [http://www.zeno.org/Schmidt-1902/A/Regiomontanus,+Johann Regiomontanus, Johann] in: ''Deutsche Buchhändler. Deutsche Buchdrucker'' vol. 5 (1908), 797f.</ref> but it is unlikely that he was actually appointed to the role.<ref name="Catholic" />

On his way to Rome, stopping in Venice, he commissioned the publication of his ''Calendarium'' with [[Erhard Ratdolt]] (printed in 1476).<ref>{{Cite web |url=https://openbook.lib.utah.edu/tag/erhard-ratdolt/ |title=Erhard Ratdolt |date=17 March 2014 |website=Open Book |publisher=[[University of Utah]]  |access-date=21 May 2019}}</ref> Regiomontanus reached Rome, but he died there after only a few months, in his 41st year, on 6 July 1476. According to a rumor repeated by [[Pierre Gassendi|Gassendi]] in his Regiomontanus biography, he was poisoned by relatives of [[George of Trebizond]] whom he had criticized in his writing; it is however considered more likely that he died from the plague.<ref name="MacTutor" />