The emergence of modern astronomy – a complex mosaic: Part II

You can read Part I here

Before we progress we need to take stock and deal with a couple of points that came up in a comment to Part I. This series is about the factors that led to the emergence of heliocentricity in Europe in the Early Modern Period. It doesn’t deal with any of the factors from earlier periods and other cultures that also explicitly and implicitly flowed into European astronomy. If one were to include all of those, it would be a total history of western astronomy that doesn’t even start in the West but in Babylon in about 2000 BCE. That is not what I intend to write and I won’t be doing so.

The other appears to contradict what I said above. At my starting point circa 1400 CE people became aware of a need to increase their usage of mathematical astronomy for a number of reasons that I sketched in Part I. Ptolemaic mathematical astronomy had been available in Europe in two Latin translations, the first from Greek the second from Arabic, since the twelfth century. However, medieval Europeans in general lacked the mathematical knowledge and to some extent the motivation to engage with this highly technical work. The much simpler available astronomical tables, mostly from Islamic sources, fulfilled their needs at that time. It was only really at the beginning of the fifteenth century that a need was seen to engage more fully with real mathematical astronomy. Having said that, at the beginning the users were not truly aware of the fact that the models and tables that they had inherited from the Greeks and from Islamic culture were inaccurate and in some cases defective. Initially they continued to use this material in their own endeavours, only gradually becoming aware of its deficiencies and the need to reform. As in all phases of the history of science these changes do not take place overnight but usually take decades and sometimes even centuries. Science is essential conservative and has a strong tendency to resist change, preferring to stick to tradition. In our case it would take about 150 years from the translation of Ptolemaeus’ Geographiainto Latin, my starting point, and the start of a full-scale reform programme for astronomy. Although, as we will see, such a programme was launched much earlier but collapsed following the early death of its initiator.

Going into some detail on points from the first post. I listed Peuerbach’s Theoricarum novarum planetarum(New Planetary Theory), published by Regiomontanus in Nürnberg in 1472, as an important development in astronomy in the fifteenth century, which it was. For centuries it was thought that this was a totally original work from Peuerbach, however, the Arabic manuscript of a cosmology from Ptolemaeus was discovered in the 1960s and it became clear that Peuerbach had merely modernised Ptolemaeus’ work for which he must have had a manuscript that then went missing. Many of the improvements in Peuerbach’s and Regiomontanus’ epitome of Ptolemaeus’ Almagest also came from the work of Islamic astronomers, which they mostly credit. Another work from the 1st Viennese School was Regiomontanus’ De Triangulis omnimodis Libri Quinque (On Triangles), written in 1464 but first edited by Johannes Schöner and published by Johannes Petreius in Nürnberg in1533.


Title page of a later edition of Regiomontanus’ On Triangle

This was the first comprehensive textbook on trigonometry, the mathematics of astronomy, published in Europe. However, the Persian scholar Abū al-Wafā Būzhjānī (940–988) had already published a similar work in Arabic in the tenth century, which of course raises the question to what extent Regiomontanus borrowed from or plagiarised Abū al-Wafā.

These are just three examples but they should clearly illustrate that in the fifteenth and even in the early sixteenth centuries European astronomers still lagged well behind their Greek and Islamic predecessors and needed to play catch up and they needed to catch up with those predecessors before they could supersede them.

After ten years of travelling through Italy and Hungary, Regiomontanus moved from Budapest to Nürnberg in order to undertake a major reform of astronomy.


City of Nürnberg Nuremberg Chronicles Workshop of Michael Wohlgemut Printed by Aton Koberger and published in Nürnberg in 1493

He argued that astrological prognostications were inaccurate because the astronomical data on which they were based was also inaccurate, which it indeed was. He had an ambitious two part programme; firstly to print and publish critical editions of the astronomical and astrological literature, the manuscripts of which he had collected on his travels, and secondly to undertake a new substantial programme of accurate astronomical observations. He tells us that he had chosen Nürnberg because it made the best scientific instruments and because as a major trading centre it had an extensive communications network. The latter was necessary because he was aware that he could not complete this ambitious programme alone but would need to cooperate with other astronomers.

Arriving in Nürnberg, he began to cooperate with a resident trading agent, Bernhard Walther, the two of them setting up the world’s first printing press for scientific literature. The first publication was Peuerbach’s Theoricae novae planetarum (New Planetary Theory)


followed by an ambitious catalogue of planned future publications from the astrological and astronomical literature. Unfortunately they only managed another seven publications before Regiomontanus was summoned to Rome by the Pope to work on a calendar reform in 1475, a journey from which he never returned dying under unknown circumstances, sometime in 1476. The planned observation programme never really got of the ground although Walther continued making observations, a few of which were eventually used by Copernicus in his De revolutionibus.

Regiomontanus did succeed in printing and publishing his Ephemerides in 1474, a set of planetary tables, which clearly exceeded in accuracy all previous planetary tables that had been available and went on to become a scientific bestseller.


However he didn’t succeed in printing and publishing the Epytoma in almagesti Ptolemei; this task was left to another important early publisher of scientific texts, Erhard Ratdolt (1447–1528, who completed the task in Venice twenty years after Regiomontanus’ death. Ratdolt also published Regiomontanus’ astrological calendars an important source for medical astrology.


Calendarius by Regiomontanus, printed by Erhard Ratdolt, Venice 1478, title page with printers’ names Source: Wikimedia Commons

The first printed edition of Ptolemaeus’ Geographia with maps was published in Bologna in 1477; it was followed by several other editions in the fifteenth century including the first one north of the Alps in Ulm in 1482.

The re-invention of moveable type printing by Guttenberg in about 1450 was already having a marked effect on the revival and reform of mathematical astronomy in Early Modern Europe.







Filed under Early Scientific Publishing, History of Astronomy, History of Cartography, History of Mathematics, Uncategorized

9 responses to “The emergence of modern astronomy – a complex mosaic: Part II

  1. “The re-invention of moveable type printing by Guttenberg in about 1450 was already having a marked effect on the revival and reform of mathematical astronomy in Early Modern Europe.”

    Re-invention? There’s so much history I have no clue about. Some beautiful printing in this post, very tight registration. I guess the illustrations and decorative elements are woodcuts?

    (Googling…) Seems like a lot of our printing technology came from China?

  2. Aiton published a translation of Peurbach’s New Planetary Theory (Osiris, 2nd Series, Vol. 3 (1987), pp. 4-43; Goldstein published a translation of the Arabic version of Ptolemy’s Planetary Hypotheses (Transactions of the American Philosophical Society, Vol. 57, No. 4 (1967), pp. 3-55;

    It should be mentioned that Peurbach’s work, like the Planetary Hypotheses, is predictively the same as the Almagest. That is, it “saves the phenomena” to the same degree. The difference is that the Planetary Hypotheses and the New Planetary Theory add extra spheres to provide a physical mechanism for the motion of the planets.

    • The Peuerbach does two things that the Almagest doesn’t do. It turns the ‘save the phenomena’ epicycle-deferent models into real spherical planetary orbits, which if you read the Almagest is what Ptolemaeus really intended. Secondly, it a comparatively simple, easy to access teaching textbook, i.e. everything that the Almagest isn’t.

  3. Thony
    There are a few papers – as abstracts – which might interest you in
    History of Science Abstracts – Annual Meeting 9–12 November 2017

    One which I found especially helpful while chasing the origin of some atypical astronomical imagery in an early fifteenth century manuscript probably made in northern Italy was this paper:
    Robert Morrison (Bowdoin College), ‘Networks and Exchange Between the Ilkhanids and the Byzantine Empire’. While it suggests the translation from Hebrew came late (and maybe the late one came west, too, we have a Jewish astronomical compendium from Spain which seems to reflect the improved learning of Maragha. But maybe something like this was the source for that ‘missing book’ you mention.
    “…a Byzantine scholar, George Chrysococcès, who traveled to Trebizond in 1347 to learn about Persian astronomy (i.e. from Marāgha), produced the Persian Syntaxis [improving and correcting Ptolemy’s Tables] a work later translated into Hebrew. A Jewish scholar from Constantinople, Mordechai Khumṭiano (d. 1485-90) authored a Hebrew text entitled Peirush luḥot Paras (Commentary on the Persian Tables), a defense of astronomical tables based on those produced under the Ilkhanids at Marāgha and Tabriz. There is no doubt that material from Ilkhanid zījes played a role in the scientific culture of Romaniot Jews and Byzantine Christian scholars. … Khumṭiano defended the Persian method against those of Ptolemy, who was favored by Byzantine scholars of the time.”

    Hope that’s not TMI

  4. Pingback: The emergence of modern astronomy – a complex mosaic: Part III | The Renaissance Mathematicus

  5. I’m loving this series Thony. More please

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