Cogs of the Cosmos: Mechanization in Renaissance Astronomy
The Visual Language of Scientific Diagrams
The tendency towards thinking about the Earth, space, and other systems as machines redefined the way in which astronomers, illustrators, and printers chose to represent celestial concepts in their books. The mechanistic worldview of the Renaissance finds expression in many pages of astronomy books, where we start to see mechanical diagrams emerge as the main visual conduits for conveying a more physical and mathematical understanding of the cosmos.
Although published after his death, this 1581 edition of Georg von Peuerbach’s Theoricae Novæ Planetarvm (see left) presents some of the most captivating mechanical illustrations of celestial objects, movements, and systems. Peuerbach, a 15th-century Austrian astronomer and mathematician linked to the humanist revival of learning, is recognized for refining planetary position calculations within the Ptolemaic system.[1] This particular text was made famous by Peuerbach's student, Johannes Regiomontanus (1436–1476), who sought to get his teacher's work to be considered the sole reliable description outlining planetary motion.[2].
The featured image on the left shows an armillary sphere as a diagram illustrating axes of orbital motion.[3] Armillary spheres, mechanical instruments used for representing the position and movement of celestial bodies, are tools with ancient origins that have been commonly employed by astronomers. Upon closer inspection, readers may also notice a clock-like device at the center, emphasizing this idea of visualizing large-scale systems as intricate machines. This diagram not only reveals early notions of celestial mechanics but also provides a visual representation of how Renaissance astronomers conceptualized the measurement of time in relation to planetary movement. Although Peuerbach's work embraced an older Aristotelian and Ptolemaic geocentric model of the solar system, his emphasis on mathematical precision and observational refinement paved the way for other "mechanist" reevaluations of the cosmos by astronomers such as Nicolaus Copernicus and Johannes Kepler. How Puerbach's ideas and calculations were visually represented by machines in this later edition showcases this drastic shift from Medieval to mechanical Renaissance cosmological perspectives.
A Shift from Medieval to Mechanical
Medieval Manuscript depiction of Earth and the Celestial Sphere, Courtesy of the British Library Board, Royal MS 19 A IX, f. 149r
Preceding the intellectual period of the Renaissance, the Medieval era was marked by its beautiful, but also deeply religious-oriented views of astronomy. This alignment of religion and cosmology found expression in medieval manuscripts of astronomy, where illustrations often portrayed celestial bodies orbiting Earth in a manner harmonious with theological tenets.
In this full-page miniature of a diagram representing the Universe from Gautier de Metz’s L’Image du monde, we can see how there was a very obvious allusion to the concept of divine influence over the cosmos. This particular diagram shows an angel and Christ being a part of the cosmos presiding over the Earth and celestial sphere [4]. While this diagram is not entirely unscientific, the manner in which the motion of the cosmos and positions of celestial bodies are artistically conveyed speaks to a worldview that is more reliant on abstract spiritual concepts, and less on mathematical and mechanical precision.
We see here how this era of pre-Scientific Revolution ideas about astronomy relied heavily upon Aristotelian ways of thinking about and depicting the cosmos. It was a view that was very anthropocentric, as it echoed an idea of the Earth and humanity's unique place within the universe.[5] This kind of thinking is much more conceptual rather than mechanical, and thus warranted such diagrams to reflect these ideas.
Moving away from manuscript culture, we begin to see more and more instances of these uses of physical models and tools being used to depict the Earth and space,and less of a reliance on symbolic religious representations. Similar to Peuerbach's diagrams seen above, the 1591 updated version Sacrobosco's Sphera Mundi (left) marks a distinctive departure from the theological depictions prevalent in medieval manuscripts. This text is widely known for being a foundational text of astronomical teachings in European universities during the early modern period.
In contrast to the symbolic and allegorical representations of the cosmos, this version of Sacrobosco's text employs armillary spheres and globes as illustrations of the cosmos. These mechanical devices are not mere adornments but serve as concrete and practical diagrams, emphasizing a shift from symbolic to empirical. By utilizing armillary spheres and globes, readers are able to gain a tangible and functional understanding of celestial mechanics. This move away from religious symbolism in favor of scientific instrumentation is emblematic of the broader intellectual shift during the Renaissance, where the cosmos became a subject of systematic study and observation, divorcing itself from purely theological interpretations.
Something worth noting about both the Peuerbach and Sacrobosco texts, is that they are still using the same Ptolemaic system of astronomy exemplified in the Medieval manuscript. That is to say, what we are seeing here is not a sudden change in the understanding of space— rather, these updated diagrams are showing a gradual evolution in worldviews that will eventually lead to broader revolutionary scientific ideas.
Astronomy and the Scientific Revolution
Armillary sphere diagrams showing two concepts of Keppler's first two laws of planetary motion.
As the ideas of mechanical philosophy and mechanism in nature began to seep into and reverberate through scientific discourse of the Renaissance, we see the publication of texts from key figures of the Scientific Revolution start to use these mechanical diagrams in the preliminary editions of their work. Using Tycho Brahe’s observations of Mars, this publication of Astronomia nova aitiologetos exhibits Kepler’s first two laws of planetary motion.[6] Looking closer at the two diagrams, we can see that the armillary spheres have been adjusted to show elliptical orbital paths, as per Keppler’s first law. Famously, Keppler’s work on planetary motion is often regarded as helping mold the mechanist shift towards understanding celestial motion.
It is in works like these that appeared during the Scientific Revolution where we not only see a concrete departure from religious symbolism central to celestial diagrams, but also a full embracement of instruments such as the armillary sphere as reliable mediums of communicating new ideas. Something to point out about the use of such instruments is, again, they are tools that were designed within an old-world scientific paradigm- that is, they would adhere to both geocentric and circular orbital mechanics. Seeing these diagrams from Keppler allows us to realize that the use of these tools in books of the Renaissance started to become updated as new theories were being proposed, almost as if the instruments themselves evolved through the printed illustrations.
What we then can definitively see is a nuanced interaction between print culture and the broader intellectual currents of the time— particularly the evolving mechanistic worldview. It becomes apparent through these diagrams that the integration of mechanical models (armillary spheres, globes, etc.) into textual representations of celestial motion was not solely for illustrative purposes but rather a manifestation of the Renaissance intellectual ethos. The mechanistic worldview, influenced by classical philosophers and a renewed interest in empirical observation, sought to explain the cosmos through the language of machines and mathematics. The inclusion of mechanical depictions in print culture was therefore a strategic choice, aiming to communicate a richer narrative about the dynamic relationship between theoretical astronomy and practical mechanics. These pages displayed here invite readers to consider the nuanced interplay between the medium of print, the visual representation of mechanical models, and the intellectual undercurrents shaping the Renaissance.
By: Ava Spurr
[1]Pantin, Isabelle. “The Illustrated Printed Page as a Tool for Thinking and for Transmitting Knowledge. the Case of the Theoricae Planetarum.” SpringerLink, January 1, 1970. https://link.springer.com/chapter/10.1007/978-3-031-11317-8_2#citeas.
[2]Ibid
[3]Puerbach, Georg Von. 1495. “Theoricae Novae Planetarum"
[4] Gautier de Metz. 1464. L’Image du monde, Low Countries (Bruges), 1464, Royal MS 19 A IX, f. 149r
[5]Shapin, Steven. The Scientific Revolution. The University of Chicago Press, 1996.
[6]Kepler, Johannes. Astronomia nova aitiologetos [romanized] Astronomia sev, Physica coelestis : tradita commentariis de motibvs stellae Martis, ex observationibus G.V. Tychonis Brahe…Heidelberg : G. Voegelinus, 1609. (Thomas Fisher Rare Book Library, University of Toronto copy gal f 00019), 42,43.
Valleriani, Matteo. 2020. De sphaera of Johannes de Sacrobosco in the early modern period: The authors of the commentaries. Springer Nature.