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

I have recently been involved in more that one exchange on the subject as to what tipped the scales in favour of heliocentricity against geocentricity in the Early Modern Period. People have a tendency to want to pin it down to one crucial discovery, observation or publication but in reality it was a very gradual process that took place over a period of at least three hundred and fifty years and involved a very large number of people. In what follows I intend to sketch that process listing some, but probably not all, of the people involved. My list might appear to include people, who at first might not appear to have contributed to the emergence of modern astronomy if one just considers heliocentricity. However, all of those who raised the profile of astronomy and emphasised its utility in the Early Modern Period raised the demand for better and more accurate astronomical data and improved models to produce it. The inclusion of all these factors doesn’t produce some sort of linear progress but more a complex mosaic of many elements some small, some simple, some large and some spectacular but it is not just the spectacular elements that tells the story but a sum of all the elements. So I have cast my nets very wide.

The first question that occurs is where to start. One could go back all the way to Aristarchus of Samos (c.310–c.230 BCE) but although he and his heliocentric theories were revived in the Early Modern Period, it was largely with hindsight and he played no real role in the emergence of heliocentricity in that time. However, we should definitely give a nod to Martianus Capella (fl.c. 410–420), whose cosmos model with Mercury and Venus orbiting the Sun in an otherwise geocentric model was very widespread and very popular in the Middle Ages and who was quoted positively by Copernicus.


The Capellan system Source: Manuscript Florenz, Biblioteca Medicea Laurenziana, San Marco 190, fol. 102r (11th century) via Wikimedia Commons

Another nod goes to Jean Buridan (c.1300–c.1358/61), Nicole Oresme (c.1320-1325–1382), Pierre d’Ailly (1351–1420) and Nicholas of Cusa (1401–1464) all of whom were well-known medieval scholars, who discussed the model of geocentrism with diurnal rotation, a model that was an important step towards the acceptance of heliocentricity.

I start with a figure, who most would probably not have on the radar in this context, Jacopo d’Angelo (c.1360–1411). He produced the first Latin translation of Ptolemaeus’ Geōgraphikḕ Hyphḗgēsis(Geographiaor Cosmographia) in Florence in 1406.


Manuscript: d’Angelo’s translation of Ptolemy’s Geography Source: Scan from Nancy Library (Hosted at Wikicommons, early 15th century).

This introduced a new concept of cartography into Europe based on a longitude and latitude grid, the determination of which requires accurate astronomical data. Mathematical, astronomy based cartography was one of the major forces driving the reform or renewal of astronomy in the Early Modern Period. Another major force was astrology, in particular astro-medicine or as it was known iatromathematics, which was in this period the mainstream school medicine in Europe. Several of the astronomy reformers, most notably Regiomontanus and Tycho, explicitly stated that a reform of astronomy was necessary in order to improve astrological prognostications. A third major driving force was navigation. The Early Modern Period includes the so call great age of discovery, which like mathematical cartography was astronomy based. Slightly more nebulous and indirect were new forms of warfare, another driving force for better cartography as well as the collapse of the feudal system leading to new forms of land owner ship, which required better surveying methods, also mathematical, astronomy based. As I pointed out in an earlier post the people working in these diverse fields were very often one and the same person the Renaissance mathematicus, who was an astrologer, astronomer, cartographer, surveyor or even physician.

Our next significant figure is Paolo dal Pozzo Toscanelli (1397–1482), like Jacopo d’Angelo from Florence, a physician, astrologer, astronomer, mathematician and cosmographer.


Paolo dal Pozzo Toscanelli. Detail taken from the 19th century honorary monument to Columbus, Vespucci and Toscanelli dal Pozzo in the Basilica di Santa Croce in Florence (Italy). Source: Wikimedia Commons

Most famous for his so-called Columbus world map, which confirmed Columbus’ erroneous theory of the size of the globe. In our context Toscanelli is more important for his observation of comets. He was the first astronomer in the Early Modern Period to treat comets as astronomical, supralunar objects and try to record and measure their trajectories. This was contrary to the ruling opinion of the time inherited from Aristotle that comets were sublunar, meteorological phenomena. Toscanelli did not publish his observations but he was an active member of a circle of mathematically inclined scholars that included Nicholas of Cusa, Giovanni Bianchini (1410 – c.1469), Leone Battista Alberti (1404 – 1472),Fillipo Brunelleschi (1377 – 1446) and most importantly a young Georg Peuerbach (1423–1461) with whom he probably discussed his ideas.

Here it is perhaps important to note that the mathematical practitioners in the Early Modern Period did not live and work in isolation but were extensively networked, often far beyond regional or national boundaries. They communicated extensively with each other, sometimes in person, but most often by letter. They read each other’s works, both published and unpublished, quoted and plagiarised each other. The spread of mathematical knowledge in this period was widespread and often surprisingly rapid.

We now turn from Northern Italy to Vienna and its university. Founded in 1365, in 1384 it came under the influence of Heinrich von Langenstein (1325–1397), a leading scholar expelled from the Sorbonne in Paris, who introduced the study of astronomy to the university, not necessarily normal at the time.


Probably Heinrich von Langenstein (1325-1397), Book illumination im Rationale divinorum officiorum des Wilhelmus Durandus, circa 1395 Source: Archiv der Universität Wien, Bildarchiv Signatur: 106.I.1840 1395

Heinrich was followed by Johannes von Gmunden (c.1380–1442) who firmly established the study of astronomy and is regarded as the founder of the 1stViennese School of Mathematics.


Johannes von Gmunden Calendar Nürnberg 1496 Source: Wikimedia Commons

Georg Peuerbach the next member of the school continued the tradition of astronomical studies established by Heinrich and Gmunden together with his most famous student Johannes Regiomontanus.


Johannes Regiomontanus Source: Wikimedia Commons

It can’t be a coincidence that Peuerbach and Regiomontanus extended Toscanneli’s work on comets, with Regiomontanus even writing a pamphlet on the determination of parallax of a moving comet, which was only publish posthumously in the sixteenth century. The two Viennese astronomers also designed and constructed improved astronomical instruments, modernised the trigonometry necessary for astronomical calculations and most importantly with Peuerbach’s Theoricarum novarum planetarum(New Planetary Theory),


Georg von Peuerbach, Theoricae novae planetarum, Edition Paris 1515 Source: Wikimedia Commons

first published by Regiomontanus in Nürnberg in 1472, and their joint Epytoma in almagesti Ptolemei, a modernised, shortened improved edition of Ptolemaeus’ Syntaxis Mathematiké


Epytoma in almagesti Ptolemei: Source

first published by Ratdolt in Venice in 1496, produced the standard astronomy textbooks for the period right up into the seventeenth century.

The work on the Viennese School very much laid the foundations for the evolution of the modern astronomy and was one of the processes anchoring the ‘modern’ study of astronomy an the European universities, How the journey continues will be told in Part II of this series.











Filed under Early Scientific Publishing, History of Astrology, History of Astronomy, History of Cartography, History of Mathematics, Renaissance Science, University History

14 responses to “The emergence of modern astronomy – a complex mosaic: Part I

  1. Laurence Cox

    I have one question about Jacopo d’Angelo and those who followed him; you say:

    “This introduced a new concept of cartography into Europe based on a longitude and latitude grid, the determination of which requires accurate astronomical data.”

    But it still took from 1406 to 1576 before Tycho Brahe started building Uraniborg. Why did no-one else make precision measurements of star and planet positions earlier. You make a good case why accurate astronomical measurements were needed, yet no-one seemed to think about making a new catalogue before Tycho? Was it just that it required someone both obsessive and incredibly rich, or were there sociological reasons?

  2. Your question is very important. In fact two people did in fact start such programmes before Tyco, as I will relate in later parts of this series. Briefly, Regiomontanus moved to Nürnberg in 1471 to do just that but died before he could really get started. Secondly, Wilhelm IV of Hessen-Kassel started such a programme in 1558 and was instrumental in Tyco beginning his own programme.

    • Ray

      I’ve also seen a number of comparisons between Tycho’s observations at Uraniborg and those of Ulugh Beg and Taqi al Din in Samarkand and Constantinople respectively. Here it seems like the age of discovery would be less of a motivation.

      Perhaps this is a digression. This first post seems quite focused on the Latin/European precedents to modern astronomy. And perhaps this is fair since by the time the Copernican revolution came to fruition it was almost exclusively a European affair, with the rest of the world catching on later. Nonetheless, I’d be curious how you see the astronomy of Toscanelli, Peuerbach and Regiomontanus in comparison to that of the rest of the world. How independent was it from astronomy elsewhere, and was it clearly more advanced in some crucial way? Would there be at the time any reason to expect that the future of astronomy was in Europe and not Muslim lands or India, or could we know only in hindsight?

      Anyway. Thanks for the post. I’m looking forward to seeing how the series progresses.

      • I find your comment, “Here it seems like the age of discovery would be less of a motivation” bizarre to say the least, as it was only one of several motivations for the study of astronomy that I listed. There is, of course, an element of astronomy for the sake of astronomy in the astronomical endeavours of all culture that practiced astronomy but the principle driving forces for the Islamic and Ottoman astronomers, as for their Babylonian and Greek predecessors, were astrology and astro-medicine.

      • Ray

        I’m not sure why you find my comment bizarre. As far as I can tell you haven’t disagreed with anything I wrote in it. The reason I referenced navigation and not astro medicine or astrology was simply that it was what seemed relevant to the comment by Laurence Cox you appeared to be responding to. I presume d’Angelo’s translation of Geographiaor Cosmographia is primarily relevant to navigation and cartography, and I had previously assumed that your selection of this translation as the formal starting point of your series was meant to highlight this motivation for astronomy as especially important in the process in comparison to other motivations which were, as you noted already present for a long time and in a range of places. (Although, interestingly, at least according to wikipedia the Geographiaor Cosmographia also existed in Arabic translation from the 9th century CE, and Arab polities had access to both the Indian and Atlantic Oceans for most or all of the centuries that followed. So this also raises the question of how Europe in the 1400s was different.)

        To reiterate, I am not saying there was anything wrong with what you wrote in the original post, but I presume you had reasons for what you chose to highlight beyond “because that is what the post is about.” That is why I asked whether and in what ways you saw 15th century European astronomy as largely independent from or more advanced than other earlier and contemporary world traditions. I’d still be interested to hear if you have more to say on that topic.

  3. The post is focused the European precedents to modern astronomy because that is what the post is about!

  4. Tony Angel

    Thank you for leading me to Martianus Capella. That has led me to John Scottus Eriugena.

    “Pierre Duhem thought that Eriugena was offering a version of the system later proposed by Tycho Brahe, and in fact Eriugena is correctly reporting Martianus’ account which seems to be a version of Heraclides of Pontus’ theory. Indeed, Copernicus would later single out Martianus for praise for his theory that Mercury and Venus orbit the sun instead of the earth. Eriugena went further than Martianus in placing Mars and Jupiter in orbit around the sun also.”

  5. Thanks for this. I’ve long been puzzled by Copernicus, whose sudden conviction of the heliocentric hypothesis seemed to come out of nowhere. I think I read somewhere that he caught the bug during his Italian sojourn, so it’s good to know that it was in the air.

    • As I will point out when I reach that point, Copernicus’ choice of a heliocentric system did indeed come out of left field but his interest in astronomy and its improvement was part of a much wider and more general movement.

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

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

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

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

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