Galileo’s Moons

A Celebration of the 400th Anniversary of the Publication of
Sidereus Nuncius (Starry Messenger)

A program sponsored by
the Rare Book & Special Collections Division and
the Center for the Book
Library of Congress, Washington, DC.
November 5, 2010

Speaker Biographies and Abstracts

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The Making of Sidereus Nuncius: From Manuscript and Sketches to Types, Woodcuts and Etchings
Paul Needham

We possess an unusually complete authorial dossier on the planning and writing of Sidereus Nuncius, a brief but complex work. Close physical examination of the surviving copies provides further information on the printing-shop production of the edition, production in which Galileo was closely involved. The Library of Congress copy is of special importance, for it is one of three copies that show the book just as it was when it left the printing shop, before trimming by bookbinders. A look at small details both of Galileo’s autograph drafts, and of the types and illustrations of the printed work, allows us to sketch a dynamic picture of how this revolutionary publication came into existence.

Paul Needham is Scheide Librarian at Princeton University, and previously worked at the Huntington Library, Morgan Library, and Sotheby’s auction house. He has published various studies on the invention and early years of European printing.

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Hearing Things: Organ Pipes, Trumpets, and Telescopes
Eileen Reeves

The opening sentences of Galileo Galilei’s Starry Messenger insist, as one would expect, on the novelty and magnificence of his recent telescopic discoveries, but the emphasis placed on the visual nature of this undertaking is curiously muted. “In this short treatise I propose great things for inspection and contemplation by every explorer of Nature,” he began. “Great, I say, because of the excellence of the things themselves, and because of their novelty, unheard through the ages, and finally because of the organ through the benefit of which they make themselves manifest to our sensory perception.” It is less the understated presentation of optical matters than the distracting suggestion that the new phenomena under scrutiny were now available for hearing. Though this reference might easily be treated as a lofty gesture to the Pythagorean notion of the Music of the Spheres, the ambiguity persists in Galileo’s subsequent allusion to the role of an organum—typically translated as an “instrument”—in his celestial discoveries. Shorn of Pythagorean pleasantries and normalizing translations, and reduced to the most flat-footed interpretation, the statement suggests an organ pipe was used to make one of Galileo’s first telescopes. There are several other allusions to the despoiled organ in early discussions of the telescope in Tuscany, but there is even more pictorial and textual information concerning a trumpet-shaped optical device throughout Northern Italy. This lecture will have as its focus that region’s tendency to associate the earliest telescope with organ pipes and trumpets for both functional and aesthetic reasons, and it will argue that the so-called occhiale a tromba was the norm, rather than the exception, in Italy for the first decade after the invention of the instrument.

Eileen Reeves is Professor of Comparative Literature at Princeton University, and she specializes in scientific literature in early modern Italy, France, and England. Her publications include Painting the Heavens: Art and Science in the Age of Galileo (1997), Galileo’s Glassworks: The Telescope and the Mirror (2008), and On Sunspots, co-authored with Albert van Helden (2010).

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Galileo on the Moon: Seen and Unseen
David Marshall Miller

Galileo’s telescopic lunar observations, announced in Siderius Nuncius (1610), were a triumph of observational skill and ingenuity. Yet, unlike the Medicean stars, Galileo’s lunar “discoveries” were not especially novel. Indeed, Plutarch had noted the moon’s uneven surface in classical times, and many other renaissance observers had also turned their gaze moonward, even (in Harriot’s case) aided by telescopes of their own. Moreover, what Galileo and his contemporaries saw was colored by the assumptions they already had. Copernicans assumed the moon was a terrestrial satellite, thus Galileo saw its mountains and Kepler “saw” the dwellings of its inhabitants. Aristotelians assumed the moon was a perfect sphere, so they saw differences in density and rarity in the lunar body. Theory corrected the results of observation, so Galileo’s lunar observations, like those that had come before, proved nothing. Yet this failure contained the germ of Galileo’s success, since the Siderius Nuncius gave observation a rhetorical force it did not have before. Observers on all sides set out to see for themselves what Galileo reported. Hence, all parties now had to answer to what they saw, whatever they believed. Thus, the Siderius Nuncius ultimately changed the grounds upon which natural philosophical argument and debate was carried out. In this new empirical arena, the Galilean science would eventually prevail.

David Marshall Miller is Visiting Assistant Professor of Philosophy and History at Duke University. He completed a PhD in History and Philosophy of Science at the University of Pittsburgh in 2006, followed by a Mellon postdoctoral fellowship at Yale University. His research examines the emergence of rectilinear space during the Scientific Revolution, and he has published papers on Galileo, Kepler, and Newton. He has also served as the Managing Editor of the Journal of the History of Philosophy.

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Galileo’s Logical Figures: Demonstration and Representation in the Dialectica, Theoremata and Sidereus Nuncius
John Hessler

It has been over a century since the philosopher Ernst Cassirer in his Erkenntnisproblem in der Philosophie first suggested that there are similarities in the logical and scientific methods of demonstration employed by Galileo and the complex theory of scientific explanation proposed by the Aristotelian commentator Giacomo Zabarella (1533-1589) in his Opera Logica, first published in 1578. In his work, which is nothing short of a full scale exposition of the history of modern thought from the Renaissance through Kant, Cassirer developed a detailed reading of the scientific revolution that relied on the re-birth of what he found to be a central Platonic idea, namely, that the application of mathematics was central to progress in science. Since Cassirer’s time, many theories of the relationship of Galileo’s scientific and mathematical methodology to Aristotelian-Scholastic logic and the Renaissance interpretations of books like Aristotle’s Physics have been proposed. Scholars in the last hundred years have put forth the full range of possibilities, from the notion that Galileo adopted the method of demonstrative regress of these commentators, or that he was a mathematical Platonist, or that he possessed no logical or methodological theory at all. To further complicate the issue of his relationship to Aristotle and medieval theories of demonstration, late in his life, Galileo professed something that has surprised and puzzled many of his interpreters. In a letter to Fortunio Liceti, written shortly before he died, Galileo implied that he had always followed Aristotle’s logical methodology, and in this sense claimed to be one of Aristotle’s students. To clear up some of these issues the following paper will present a new reading, from a modern philosophical perspective, of Galileo’s concepts of logical methodology as it is found in his unpublished manuscript (BNF GAL.27), the Dialectica, which contains his notes on Aristotle’s Posterior Analytics, and of his early mathematical work the Theoremata circa centrum gravuatus solidorum.

We will show how examples of Galileo’s early demonstrative methods can be found not only in these texts, but also, and more clearly, in his illustrations and in his discourse about the moons of Jupiter in the Sidereus Nuncius. The illustrations, which are designed and executed to show motion, are radically inventive in their form and in what they are trying to prove. But besides their inventiveness, they clearly show Galileo’s new demonstrative paradigm in schematic form, and display diagrammatically his rejection of the form of regressus found in the commentaries of Augustino Nifo (1473-1538) and Giacomo Zabarella, and his adoption of a much more geometrical notion of logical demonstration. Galileo’s observations of Jupiter’s moons were not only scientifically innovative, but also, and on a more conceptual level, forced notions of realism into astronomy that did not exist before, creating the need to theorize the place of mathematics, the role of instruments, and form of the logic employed in scientific discovery.

John Hessler is currently Senior Cartographic Librarian in the Geography and Map Division of the Library of Congress. A Fellow of the Royal Geographical Society he has written extensively on the history and mathematics of cartography and astronomy and has published articles and reviews in many journals including Applied Physics Letters, Complex Analysis and Geometry, Imago Mundi, Cartographica, the Journal of the Washington Map Society and Coordinates. He is the author of a new commentary and translation of Martin Waldseemüller’s seminal text, the Cosmographaie Introductio, entitled The Naming of America: Martin Waldseemüller’s 1507 World Map and the Cosmographiae Introductio (January, 2008). He is currently working on a compendium of annotations in Renaissance logic texts and commentaries and on a forthcoming translation and commentary of Johannes Schoner’s and Regiomontanus’ Doctissimi viri et mathematicarum disciplinarum eximii professoris Ioannis de Regio Monte De triangvlis omnímodis libri qvinqveto (On Triangles of Every Sort) to be published by the Bibliotheca latinitatis novae in Leiden in 2011.)

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Galileo’s Copernican Conversion
Owen Gingerich

Although Galileo admitted to Kepler as early as 1597 that he accepted the heliocentric cosmology, he remained a timid Copernican until his newly devised telescope revealed novelties in the heavens, the discoveries reported in his Sidereus Nuncius of 1610. Careful examination of his lunar drawings reveals an observer more interested in topography than cartography. Galileo was interested in the heights and depths that mimicked the earth, an important challenge to the classical Aristotelian dichotomy between the terrestrial and the celestial. The Milky Way was unveiled as hitherto unsuspected congeries of stars, demonstrating the inadequacy of prior views. And Jupiter with its retinue of satellites, a veritable miniature Copernican system, afforded a particularly interesting rebuttal to those who refused to accept the Copernican cosmology because they could not believe that the earth would be able to keep the moon in tow if it wheeled around the sun. Because the Sidereus Nuncius was in effect Galileo’s job application for a position in the Florentine court, he did not dare to produce a bold polemic in favor of the heliocentric system, but nevertheless an intelligent audience who could read between the lines began to appreciate the dynamite implications of this epoch-making starry message.

Owen Gingerich is Professor emeritus of Astronomy and History of Science at the Harvard-Smithsonian Center for Astrophysics in Cambridge. He has written the ironically titled The Book Nobody Read about his Copernican researches (2006). Among his 750 published articles and reviews are “From Occhiale to Printed Page: The Making of Galileo’s Sidereus Nuncius” (with Albert van Helden) in Journal for the History of Astronomy (2003), and “The curious case of the M-L Sidereus Nuncius” in Galilaeana (2009).

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Reception and Influence of Galileo’s Sidereus Nuncius (and the fate of Galileo)
Peter Machamer

Galileo’s Starry Messenger, published in 1610, received almost immediate affirmation and support, especially from the Jesuits of the Collegio Romano. There were a few dissenters, and those were not taken seriosuly. The book enabled him to get a job as philosopher and mathematician at the Medici court in Florence. From there on he seemed to go from success to success. Indeed, Cardinal Barberini (around 1612) wrote a laudatory poem about Galileo and his work. Then in 1616 Copernicus’ Revolutions of the Heavenly Orbs was placed on the Index of forbidden books (pending correction), and Galileo was called before Cardinal Bellarmine and enjoined not to hold, teach, or defend the Copernican doctrines that the sun stands still at the center of the world and that the earth moves. Earlier, Galileo’s Letter to Grand duchess Christina (1615) began to provoke much controversy.

Galileo continued to write, disseminate, and publish his opinions. In 1623 Cardinal Barberini was elected Pope, and took the name Urban VIII. By 1630 Galileo had competed his book, Dialogues on the Two Chief World Systems. I n 1632 the book is published in Florence, with a Florentine imprimatur. Approximately 6 months later, Urban VIII forwards the case against Galileo to the Inquisition. In June 1633 Galileo is sentenced, and recites a formal abjuration.

The Galileo affair has begun. Controversy still continues until this day.

Peter Machamer is professor of History and Philosophy of Science at the University of Pittsburgh, an associate director of Pitt’s Center for Philosophy of Science, and a member of the center for the Neural Basis of Cognition. He is the editor of The Cambridge Companion to Galileo (1998) and has written extensively on 17th Century science and philosophy. Most recently he published with J. E. McGuire, Descartes’ Changing Mind (Princeton University Press, 2009).