The astronomical revolution didn’t start here!

In the usual collection of myths that passes for history of science in our culture the astronomical revolution (and the so-called scientific revolution for that matter) is considered to have started with the publication of Copernicus’ De revolutionibus in Nürnberg in 1543, however the evolution of the new astronomy had already been in full swing for at least 140 years before this event. One of those who made major contributions to this evolution, before Copernicus was even born, was the mathematician, astronomer and poet Georg Aunpekh who was born in the Upper Austrian village of Peuerbach on 30^th May 1423. Like most humanist Renaissance scholars Aunpekh adopted a Latinised toponym as his professional name and so he is better known as Georg von Peuerbach or simply Peuerbach.

Nothing is known about Peuerbach’s origins and early education but he entered the University of Vienna as a student in 1446 at the age of 23. This was unusually late in an age when students normally started their studies at the age of fourteen and in fact Peuerbach had already spent a couple of years living and travelling in Northern Italy where he acquainted himself with the then new and revolutionary humanist learning. In Rome he had shared an apartment with Nicolas Cusanus and on his travels he had met and become friends with the leading Italian mathematicians such as Giovanni Bianchini (1410 – c.1469) and Paolo Toscanelli (1397 – 1482). In Vienna he graduated BA in 1448 and MA in 1451 and began teaching dialectic and poetics. Alongside his official teaching duties he also taught astronomy and mathematics, continuing a tradition started by Johann von Gmunden (c. 1380 – 1442), as can been seen from the dates Gmunden was not Peuerbach’s teacher as is stated in many sources. Gmunden and Peuerbach together with Peuerbach’s most famous pupil Johannes Müller, better known as Regiomontanus, constitute what is known as the 1^st Viennese School of Mathematics and their combined efforts form as significant part of the advances made in astronomy, mathematics and instrument making in Europe in the 15^th century. During his all too short lifetime Peuerbach also served as court astrologer to King Ladislav V of Hungary and Bohemia from 1454 to 1457 and the after his death court astrologer to the German Emperor Frederick III.

In 1450 the then 14 year-old Regiomontanus entered the University of Vienna where he became first a student of Peuerbach’s and then after graduation his friend and colleague, although disciple might be a more appropriate term. Together they studied and made significant advances in all the branches of the mathematical sciences as they were practiced at that time. In particular Peuerbach made important contributions to the calculation of sine tables, the observation of comets and the construction of various scientific instruments. He is credited with being the first person to recognise and compensate for magnetic deviation, that is the difference between true north and magnetic north and to produce compasses compensating for the local deviation. Because the magnetic poles wander deviation is not constant but varies from place to place and with time.

In 1460 the Greek Papal legate Basilios Bessarion came to Vienna on a diplomatic mission. Bessarion was one of the leading European humanist scholars and a passionate fan of the mathematical sciences and so he quickly sort out the company of Peuerbach. One of Bessarion’s philosophical rivals Georg of Trebizond, also Bessarion’s birthplace, had recently made a new Latin translation of Ptolemaeus’ Syntaxis Mathematiké from the original Greek that Bessarion regarded as inferior and full of errors, a fairly accurate judgement, and so he asked Peuerbach to produce a new translation. Peuerbach’s Greek was not up to the task but knowing the Syntaxis intimately he did agree to produce a modernised, simplified version of the text. Bessarion also invited Peuerbach to become a member of his household and accompany him back to Rome when his mission in Vienna was completed. Peuerbach agreed on the condition that Regiomontanus could go with them. However Peuerbach feel ill and died in 1461 at age of 39 having only completed the first six books of his edition of the Syntaxis. On his deathbed he extracted the promise from Regiomontanus to finish and publish this important work.

Regiomontanus went of to Rome with Bessarion and after many adventures, that will be dealt with in a separate post, he settled in Nürnberg in 1471 where he set up the worlds first printing press for scientific books. His first publication, and the first ever printed mathematical book, in 1472 was Theoricarum novarum planetarum (New Planetary Theory) based on the lecture notes of his teacher Peuerbach. This book set out to find a workable compromise between the homocentric cosmology of Aristotle and the deferent epicycle astronomy of Ptolemaeus embedding the Ptolemaic mathematical constructions in homocentric spheres. For many centuries this work was thought to be an original contribution from Peuerbach until an Arabic translation of Ptolemaeus’ own cosmology, unknown up till then, was discovered in the 1960s and it became clear that Peuerbach was just reproducing Ptolemaeus’ own theories. Regiomontanus had completed Peuerbach’s digest of the Syntaxis during his time in Italy, learning Greek from Bessarion for the purpose, but he himself died in 1476, barely older than his teacher, before he could publish it. The book their Epytoma in almagesti Ptolemei was published in Venice in 1496. The two books formed the basis for the teaching of astronomy for the next 150 years with Peuerbach’s New Planetary Theory going through at least 56 editions by 1653. All of the great astronomers of the 16^th century, including Copernicus, learnt their astronomy from Peuerbach’s books.

To close I would like to mention another aspect of Peuerbach’s life and work that usually gets ignored in works on the history of science. Peuerbach is one of the few examples, before the 20^th century, of a scientific scholar who was known to be homosexual. I think this fact should be made public more often to help combat the ignorance and hate that some people feel necessary to pour out against the lesbian and gay community. Peuerbach’s partner or lover was a monk who committed suicide and the heartbroken Peuerbach erected a monument to his dead love in a series of beautiful love poems written in Latin. Peuerbach was not only a great astronomer but also a more than competent poet. A combination of strange bedfellows that would re-emerge in Vienna at the beginning of the next century with Conrad Celtis’ College for Poetics and Mathematics and the Second Viennese School of mathematics but that is as they say another story.