various astronomy-related historical images

Biennial History of Astronomy Workshop - ND X July 6-10, 2011

Abstracts (listed alphabetically)

Barbara Becker, University of California, Irvine
“William Huggins and George Ellery Hale: An Uncommon Partnership to Secure the Future for the New Astronomy”
William Huggins met George Ellery Hale for the first time in August 1891. By then, the sexagenarian English amateur astronomer was renowned as the “father” of the new astronomy of astrophysics. Hale, who was born just one month after Huggins read his watershed paper on stellar motion in the line of sight, never knew a time when astronomy was practiced without spectroscopy. Despite their age difference, the two men had a lot in common and kept up an active correspondence until William’s death in 1910. As this paper will show, their unpublished correspondence reveals that they enjoyed a symbiotic relationship with each giving as much as he gained to satisfy their united appetite for promoting the development and wider application of spectroscopic methods in astronomy. By the turn of the twentieth century the “new astronomy” had matured into a technically and conceptually demanding enterprise that could be managed only by the few who possessed the instruments, skills, and financial resources needed to stay competitive. When, near the end of his life, Huggins recognized that he no longer possessed the tools, expertise, and youth necessary to finish the race he had started, he prepared to pass the baton on to those who did: astronomers like Hale who called themselves astrophysicists.

Trudy E. Bell, Science/Technology Writer and Editor
“Astronomical Inventions of George Washington Hough”
George Washington Hough was a U.S. astronomer known during the nineteenth century especially for his dozens of clever and useful astronomical and meteorological inventions, his discovery of 648 double stars, and four decades of meticulous visual observations of Jupiter. But even as early as the time of his death in 1909, he had fallen into such obscurity that obituaries and other secondary sources conflict about basic facts of his life (such as what degrees he had earned and from where, and the full number of his publications). Published sources are also silent about exactly where he was and what he was doing for fully five years: from 1874, when he left his post as director of the Dudley Observatory when the observatory was temporarily closed, until 1879, when he became director of the Dearborn Observatory in Evanston, Illinois, where he remained for the last four decades of his life.

Unpublished correspondence and other documents at eight institutions—the Albany Institute, the Cincinnati Observatory, the University of Cincinnati, the Cleveland Public Library, the Dudley Observatory, Notre Dame University, Northwestern University, and Union College—reveal that his meteorological inventions apparently got Hough into unrealized trouble with the trustees of the Dudley Observatory. Moreover, the observatory’s sudden temporary closure in 1874 amounted to a de facto dismissal, which left Hough bitter and suffering in a private hell for the next five years.

This illustrated talk will demystify several shadowy unknowns of his life story and highlight a dozen of his key inventions, including his automatic star-charter and his self-registering barometer.

This research was supported by the 2007 Herbert C. Pollock Award of the Dudley Observatory.

Gary Cameron, Iowa State University
“The Victorian and the Modern: Telescopes and the Aesthetics of Design”
Most small telescopes (those often sold to schools and amateur astronomers) of the nineteenth and early twentieth century generally followed very similar design characteristics. They consisted of refracting optics, polished brass tubes, decorative details, and elaborate mahogany tripods. They were aesthetically pleasing to many at the time and not at all out of place standing in the finest Victorian parlor or conservatory. However, beginning with telescopes produced by the firm of Carl Zeiss Jena (Germany) around 1900, the aesthetics of telescope design changed to far more utilitarian and modernistic patterns. New telescope manufacturers, such as Zeiss, Tinsley (USA), and others, marketed telescopes with tubes of white enameled steel, aluminum, or even fiberglass; many decorative parts were made more streamlined and functional; and the reflecting telescope gained in popularity as being more “useful.” There were a number of reasons for these changes, but it is clear that the design philosophy of telescopes, and scientific instruments generally, largely paralleled, or even preceded, modern design schools such as Art Deco, Bauhaus, and Futurism. Such changes in design philosophy are important in explaining the rise of new telescope manufacturers and the failure of old ones in the context of material culture, modern society as a whole, and changing aesthetic tastes in the twentieth century.

Stephen Case, University of Notre Dame
“The Origins of John Herschel’s Double Star Astronomy”
Research on the origins of double star astronomy has focused on double stars as targets that allowed astronomers to utilize precision instruments and develop new mathematical tools for calculating orbits. While the British astronomer John Herschel (1792-1871) was an integral part of this work, he also was interested in questions regarding the nature of these celestial objects. Herschel’s early thoughts on double stars and his motivations for beginning research on these objects have not been previously examined. My paper will use Herschel’s correspondence to explore the origins of his work on double stars, focusing on the interrelated considerations of stellar parallax, obtaining proof of his father William’s theory on the binary nature of certain double stars, and speculations on the possibility of detecting planets in orbits around other stars.

John Cirilli, University of Notre Dame
“The Objectives and Art of Golden Age Islamic Astronomy”
During the thirteenth to sixteenth centuries, which George Saliba dubs “the Golden Age of Islamic Astronomy,” astronomers (many of the Maragha School) in the Islamic east developed highly sophisticated alternatives to Ptolemaic astronomy. Answering Ibn al-Haytham’s demand for complete conceptual consistency in mathematical astronomy and, perhaps, al-Ghazālī’s admonition to metaphysical tentativeness, scholars such as al-Tūsī, al-’Urdi and al-Khafri combined mathematical and descriptive rigor with ontological open-mindedness and created a distinct and distinctive astronomical tradition. They devised numerous models, al-Khafri, for example, creating multiple mathematical representations for precisely the same motions, without insisting upon their reality. They apparently valued these successive models not solely or even primarily for predictive accuracy, which, along with conceptual consistency, they had already achieved. Their primary motivation cannot therefore have been strictly “philosophical” either, at least in terms of logic and metaphysics, as, satisfying the first, they abstained from the latter. Their continued production of models, absent another motivation, suggests that they created them because they wished to, because astronomy was for them a medium for virtuosity. Neither fundamentally realist nor nakedly instrumentalist, they had become artistic. That none of them developed Copernican heliocentrism while devising many of the mathematical tools Copernicus himself employed perhaps reflects this non-metaphysical turn. Copernicus shared with them the goals of mathematical consistency and empirical accuracy, but also had what thorough inculcation of their discipline’s goals and boundaries may have precluded: a preparedness to pronounce a given configuration “real.” Their model-making had taken on a life of its own.

Ariel Cohen, The Hebrew University of Jerusalem
“The Bible as a History of Astronomy Sourcebook: The Ages of the Biblical Patriarchs as Derived from the Ancient Epicycle Model of the Orbit of the Sun”
I demonstrate that the sun-moon conjunctions occurring at the beginning of the Zodiac signs taking into account the Real Sun’s orbit correspond to a most ancient detailed astronomical set of data shown to be embedded in the chronology of the Septuagint version of the bible. I show that the birth-ages of the Biblical Patriarchs from were calculated with the assumption that they coincide with such conjunctions.

Since the Septuagint version is assumed to have been translated in the third century BC from an earlier existing Hebrew source, it is revealed as one of the very first ancient scientific sources containing detailed data which led to the development of all astronomical models that determined the real planetary orbits.

I finally demonstrate how the detailed evaluation of the biblical data leads to the individual sizes of the constellations predating the data presently published by NASA and the Naval Observatory.

Dennis Danielson, University of British Columbia
Panel: “‘Philosophical truly averred’: In Search of Astronomical Truth(s) 1576-1651””
This session will focus on aspects of the work of four scientists—Thomas Digges, Thomas Harriot, Johannes Kepler, and Giovanni Battista Riccioli, respectively— who over a span of seventy-five years, from 1576 to 1651, sought by theoretical, mathematical, logical, and observational means to promote an astronomy worthy of the name philosophical. Simply put, these four—not all of them adherents of Copernicanism, and before a single model of the universe fully took hold—aimed in various ways not to “save the phenomena” but to attain as closely as they might truths about the actual physical character of the world. These presentations promise both to be informative individually and as to contribute collectively to a wider discussion of the theme of philosophical approaches to astronomy during roughly the first century of Copernicanism.

Dennis Danielson, University of British Columbia
“Thomas Digges: Making the Incredible Credible”
Thomas Digges, who distinguished himself as Copernicus’s very first (and only published) sixteenth-century translator, is also well known for offering a diagram of the Copernican universe whose boldest feature is a starry realm—unlike the bounded sphere of De revolutionibus — that continues “infinitely up.” Just as relevant to discussions of how Copernicanism eventually took hold, however, are the “conservative” elements both in Digges’s graphic and in his rhetoric. A close reading of A perfit description of the Caelestiall Orbes reveals Digges’s skill at offering his readers “lifelines” that permit them to ponder the power of the Copernican system without having to relinquish all of the elements (including elements of Aristotelian physics) that until then had seemed to give their physical world its coherence. At the same time, however, Digges offers the Copernican model not as any mere hypothesis but as a proposal “philosophical truly averred.”

Astrid Elbers, Leiden Observatory
“The Relations between Dutch Radio Astronomers and Their Soviet Colleagues during the Heyday of the Cold War”
After the Second World War, a new scientific field came into being: radio astronomy. This field originated from wartime radar technology and developed worldwide. From the start, the field was characterized by extensive international exchange. However, the Cold War seriously limited contacts between Western and Eastern scholars. In the Soviet Union, internationalism was damned and replaced with a militant Soviet nationalism. Scientists were forced to resign from foreign scientific societies, foreign visits were minimized, and the publication of Soviet research in foreign languages was forbidden. As a consequence, the interaction between Soviet and Western radio astronomers was very weak.

One of the first major postwar radio astronomy groups was located in the Netherlands. Dutch radio astronomers—unlike most of their colleagues in other countries—made considerable efforts to involve Soviet radio astronomers in the ongoing research.

In my paper, I will explore how and why the Dutch were so eager to establish international contacts with the Soviets. As we will see, pragmatic considerations outweighed the idealistic. On the other hand, I will explore how Soviet radio astronomers reacted to the efforts of their Dutch colleagues. It is striking that the Soviets had often no choice but to condemn Western science openly in their own country, while at the same time having very good contacts with their Dutch colleagues.

Jorge M. Escobar, University of Notre Dame
“A False Dichotomy in Kepler’s Celestial Physics”
Kepler is usually regarded as one of the most important early modern figures in the rise of mechanistic approaches to nature. His view of the world as a clock is typically taken as a paradigmatic example of this kind of approach. However, some recent interpretations of his natural philosophy tend to emphasize the presence of vitalist elements in his celestial physics, particularly concerning his explanation of the origin of comets and new stars. These vitalist, nonmechanistic elements become problematic because they point to an important internal tension in Kepler’s natural philosophy. On the one hand, Kepler would have thought of the world as an inanimate thing, a machine, when he had to deal with issues such as the motion of the planets. But on the other hand, he would have thought of the world as an animate thing, a living being, when he had to deal with issues such as the origin of comets and new stars. I argue here that despite the important findings of these recent studies regarding topics like the Earth soul, this is in fact a false dichotomy. The explanation of the origin of comets and new stars completely agrees with the mechanical explanation of other natural phenomena in Kepler’s world, whereas the notion of an animate world is an unjustified inference from certain passages of his work.

Jacqueline Feke, Stanford University
“Ptolemy’s Philosophical Defense of Astronomy”
In the introduction to the Almagest, Ptolemy justifies his decision to spend most of his time on mathematics, and astronomy in particular. This justification is philosophical. Appropriating Aristotle’s tripartition of theoretical knowledge, Ptolemy defines mathematics in juxtaposition with the other theoretical sciences, physics and theology. Ptolemy defines physics, mathematics, and theology according to their objects of study, and he evaluates their respective epistemic success. Ptolemy argues that physics and theology are conjectural and that mathematics alone yields knowledge. In other words, mathematics is the only science that produces justified, true hypotheses of the cosmos. This argument is unprecedented in ancient Greek philosophy and controversial for the second century. Having asserted mathematics’ epistemic superiority, Ptolemy proceeds to expound on the ethical benefits of studying mathematics, especially astronomy. Revising the Platonic propaedeutic evaluation of astronomy, Ptolemy maintains that the study of astronomy is valuable in itself. By contemplating the mathematical qualities of celestial objects, the astronomer reforms his soul into a state that is similar to the divine celestial one. With this paper, I present Ptolemy’s multifaceted defense of astronomy by analyzing his metaphysics, epistemology, and ethics of astronomy.

Owen Gingerich, Harvard University
“Eclipsing the Myths of Kepler’s Ellipse”
The textbook exaggerations of Kepler’s subtle eclipse have led generations of students to wonder why something so seemingly obvious hadn’t been found centuries earlier. Watch out for the difference between eccentricity and ellipticity! Don’t be misled by Kepler’s triangulation diagram for finding the shape of Mars’ orbit. And never dismiss his Trinitarian cosmology as simply another example of Kepler’s mystical nuttiness! This paper will unfold the great Martian catastrophe of 1593 and how Kepler, using his remarkable physical sense, fixed it.

Robert Goulding, University of Notre Dame
“Perspective Trunks and Burning Glasses: Harriot’s Optical Theory and His Telescopic Observations of the Moon”
In July 1609, Thomas Harriot turned a 6-power terrestrial telescope towards the moon, and made a crude sketch of what he saw—the very first record of optically aided astronomical activity, made several months before Galileo’s much finer (and historically more significant) telescopic images of the moon. Unlike Galileo, Harriot had been studying mirrors and lenses for more than a decade before his construction of his first telescope. This paper will explore the manuscript notes of Harriot and some of his associates on the powers of lenses and the formation of images, in order to suggest the path Harriot took to the telescope—one quite different from that taken by Galileo.

Chris Graney, Jefferson Community & Technical College
Panel: “Using Historical Materials in Teaching Astronomy: A Panel Discussion”
Panel members will discuss their experiences of using historical materials while teaching courses in which students are expected to learn astronomy. Panel members include: Michael Crowe (University of Notre Dame), Bill Donahue (St. John’s College Santa Fe), Alan Hirshfeld (University of Massachusetts Dartmouth), Owen Gingerich (Harvard University), Chris Graney (Jefferson Community & Technical College [KY]), Todd Timberlake (Berry College [GA]), and Barbara Becker (University of California, Irvine).

Christopher M. Graney, Jefferson Community & Technical College
“Giovanni Battista Riccioli’s Review of the Case for and Against the Copernican Hypothesis”
In his 1651 Almagestum Novum the Italian Jesuit astronomer Giovanni Battista Riccioli reviews for-nine arguments for and seventy-seven arguments against the Copernican Hypothesis, stating that the weight of evidence is against Copernicus. Later writers have often described this work as being simply a listing of arguments, with the decision in favor of Copernicus being decided by weight of numbers, and by biblical or ecclesiastical authority. Riccioli himself is often characterized as a secret Copernican who undertook this exercise owing to his duty as a Jesuit priest.

The arguments of the Almagestum Novum, now rendered into English, show that the debate over the Copernican Hypothesis, as summarized by Riccioli, was dynamic and scientific, with its key issues being matters of observation and measurement both in physics and astronomy. For example, only two of the seventy-seven “against” arguments that Riccioli gives are related to religious matters (and Riccioli dismisses both), while the key arguments he gives are those involving telescopic observations of stars and those involving trajectories of projectiles and falling bodies in Earth’s rotating frame of reference (in today’s terms, those involving the Coriolis effect). Riccioli’s key arguments are powerful—they went on to become matters of further investigation even after the Copernican Hypothesis was widely accepted—and not at all the work of a secret Copernican. Riccioli’s work casts a different light on opposition to the Copernican Hypothesis, and on how that opposition has been portrayed in the history of astronomy.

Thomas Hockey, University of Northern Iowa
“My Reflection on the Telescope’s Four Hundredth”
2009’s International Year of Astronomy brought forth a prodigious amount of literature on the telescope and its influence in science, society, and even art. Yet philosophers were oddly absent in recognizing the four-hundredth anniversary of this remarkable instrument. They have not been so in regard to the telescope’s cousin, the microscope.

Both the telescope and microscope have extended human senses and are the basis for many scientific achievements, some of which save our lives. Yet philosophers of an idealist persuasion question the microscope as a conduit to reality. The argument goes something like this: The telescope, at least, shows us objects that we could, in theory, visit and scrutinize at close distance—planets and stars. The microscope shows us objects in an inner world that we can never call upon ourselves.

Regardless of what you believe about the microscope, this old special pleading for the telescope I find naïve today. I will present an argument in which the microscope and telescope are equivalent in that they both allow us to “visit” places to which we could never travel through space and time.

JC Holbrook, University of California Los Angeles
“Women, Minorities, and Databases”
More and more telescopes are being built that are fully automated with huge amounts of data that pass through a data pipeline and are automatically integrated into large databases that eventually are made public. This new astronomy data practice holds promise for transforming the field of astronomy in several ways, two ways of interest for this project is that anyone can access the databases and that new astronomy questions can be explored using the databases. An NSF-funded project to study women and minority astronomers and their practices related to large database driven projects was begun in 2009. The majority of the interviews conducted for the project focus on the Infrared Processing and Data Center (IPAC), the Large Synoptic Survey Telescope (LSST), and the Sloan Digital Sky Survey (SDSS). The hypothesis for the project is that women and minority astronomers have utilized “meshworks” to get involved in the astronomy projects named as well as to advance their careers. Meshworks can be thought of as bundles of connections that are complexly interwoven as compared to networks. This presentation will explore just one of the preliminary findings of the project: that women and minority astronomers have been brought into these database-driven collaborative projects laterally by peers rather than by invitation from senior astronomers. The presentation will include a project overview including data collection methods that include recording oral histories. The conclusions will consider the robustness of the preliminary finding. A possible topic for further discussion is characterizing the place of the emerging field of “astroinformatics” in astronomy—is it a sub-discipline or its own discipline, another method like the programming necessary for cosmological models, or it is something for technicians (read: non-astronomers) to do?

Stephen C. McCluskey, West Virginia University
“The Variety of Celestial Circles”
From antiquity to the present, astronomers have discussed a variety of imaginary circles which served different functions in their astronomical theory and practice. Earlier studies of celestial circles have considered celestial circles as an unproblematic concept, treating them all as the same kind of imaginary mathematical entities, yet this approach overlooks the existence of different kinds of celestial circles. At one extreme are those circles that are imagined as coordinates (the most extreme case of this sort would be the colures, which have no direct relation to any moving celestial body). Then there are those circles that reflect the annual motion of the Sun or planets (the ecliptic) and those circles that represent their daily motion—the 183 daily circles mentioned by Martianus Capella or the seven relating daily motion to the zodiac mentioned by Ptolemy. Finally, there are those circles, such as eccentrics and epicycles that are imagined to account for the more complex motions of celestial bodies. Although the latter are mathematical entities, they also operate as formal causes.

I intend to discuss some historical examples of these circles and address their philosophical implications, particularly how they were related to mathematical or physical entities.

Erik Norquest
“Uniting Theory and Observation: Otto Struve as First Mover in Astrophysics”
From 1936 to 1950, few astronomers could claim as heavy an influence on astrophysics as Otto Struve. As the director of two major observatories—Yerkes in Wisconsin and McDonald in Texas—and the editor of the Astrophysical Journal, Struve held a unique position in the administrative apparatus of astrophysics. When combined with a constant stream of published scholarly works, this position made Struve a dominant agent and “first mover” in the field of astrophysics. Struve created for himself a nexus of what Pierre Bourdieu calls “scientific capital.” From this nexus he was able to shape the field of astrophysics according to his own beliefs of what astrophysics should be. To this end, Struve set about attempting to unite theory and observation in a way that had not previously been accomplished.

Marc Rothenberg, National Science Foundation
Panel: “Funding the History of Astronomy: The Role of the National Science Foundation, Past and Future”
Although the National Science Foundation is a major supporter of the history of science in the United States, the number of awards given for the history of astronomy is relatively low. Since 1985, and counting archeoastronomy and dissertation awards, the NSF has supported approximately sixty proposals. This session will include brief presentations by historians of astronomy who have during the last few years, been successful in getting NSF support, in which they will address the role of the NSF in their research. This will be followed by discussion on how to increase NSF support for the history of astronomy. Participants will include: Patrick Boner (Johns Hopkins University), Marvin Bolt, (University of Notre Dame /Adler Planetarium), David DeVorkin (National Air and Space Museum, Smithsonian Institution), Frederick Kronz (National Science Foundation), and Marc Rothenberg (National Science Foundation).

Morgan Saletta, Melbourne University
“The Functional Equinoctial Alignment of the Arles-Fontvieille Monuments: The Equinoctial Hierophany, the Pleiades, and Orion”
Based on my ongoing research into the sites, I will present evidence of a functional solar equinoxal alignment of the Arles/Fontvieille monuments. I will also suggest a probable association with the Pleiades and the constellation of Orion of at least one of the sites. The talk will present evidence for both claims, including photographic documentation of a functional and hitherto undocumented purpose of the astronomical alignment of the sites. The functional nature of the equinoctial alignment can presently be demonstrated for three of the five sites.

The large and impressive Neolithic monuments of Arles/Fontvieille appear to have been at the center of a major local megalithic culture that extended its influence over the local territory as evidenced in the orientation of megalithic monuments of the surrounding area. These monuments, frequently termed hypogées, are some of the largest, most impressive, and probably among the most important Neolithic monuments in France and Europe.

These subterranean monuments are aligned on an east/west axis, opening on the west. It will be proposed that these monuments have a functional astronomical alignment to the equinox sunset such that a large shaft of sunlight penetrates the long passage and strikes the back wall, producing a striking hierophany. There is a spectacular display of illumination in the one site whose opening is unobscured by plant growth and is visibly present at two of the others. Unlike the so-called passage tombs or passage mounds of the British Isles, Ireland, and Brittany, the Arles/Fontvieille monuments are subterranean, and it is not at all obvious that it would be possible for the sun rays to penetrate these passages or hypogées at all, at least to any depth, let alone to their entire length as documented by the author.

While the east/west orientation of the monuments has been noted by several authors as being toward the setting equinox sun, and recently researchers have highlighted this unusual orientation within the context of European and Mediterranean megalithic orientations, the possible functional (in terms of producing a hierophany) nature of this alignment seems to have been entirely ignored for a number of reasons, including the difficulty of access to all but one of the sites.

It is my contention that in order to understand the place of these important monuments within the European Neolithic, the discovery of a functional phenomenon of the astronomical alignment of these sites is of fundamental importance. It may shed light on the relationship of these sites to other European monuments as well as indicating the need for similar investigations of sites where such phenomenon may have been overlooked in the past. To this purpose these sites need to be examined within a large geographical context and within an analysis of the way cosmological knowledge, ritual practice, belief, and social power were constructed into the landscape and territory in the form of these monuments.

Peter J. Susalla, University of Wisconsin-Madison
“Philosophy, Physics, and the Meanings of ‘Cosmology’ in the Twentieth Century”
Historians currently use the term “cosmology” in two primary, related ways: first, as a physical theory of the universe or the practice of such conceptual work and, second, as a cultural worldview. However, we know little about how such meanings developed. This paper explores the history of the English term “cosmology” in the twentieth century. In particular, I show that the most prominent uses of the term in the early years of the century were in philosophy, where the word was a well-established label for a branch of metaphysics, and in historiography, where the term meant a physical model or picture of the universe. With the development of new relativistic models of the universe in the 1920s and 1930s, physical scientists, for the first time, began to employ “cosmology” widely in their work. Yet, as debates during the interwar and early Cold War years suggest, physicists’ new usage of “cosmology” both retained older, historiographical uses of the term as a picture or model and represented an attempt to demarcate the new cosmology as “science” and not metaphysics. I focus on the writings and addresses of the physicists Richard Tolman and Hermann Bondi and the philosophers Herbert Dingle and Milton Munitz in arguing that one of the current meanings of “cosmology”—a branch of the physical sciences—was the product of decades of philosophical and scientific negotiation. Finding space for “cosmology” within the physical sciences was neither an easy nor an inevitable process.

Sarah Symons, McMaster University
“Comparison of Near-horizon Astronomical Events Recorded in Ancient Egyptian Diagonal Star Tables”
Diagonal star tables are Egyptian hieroglyphic texts listing the configuration of certain stars during the night at ten-day intervals. Most of the tables are found on coffin lids dating to the First Intermediate Period and early Middle Kingdom (around 2150 BC). Twenty-two examples are known, of which one will be presented here for the first time.

Each column of a diagonal star table typically contains twelve star names. Stars which occur in these tables are known as “decans.” The complete, ordered set of stars in a table (spanning up to forty such columns and more than forty stars) is called a “decan list.” Previous attempts have been made to classify the tables into groups or taxonomies by considering details of layout. However, with further sources identified, only one classification criterion emerges as significant: the decan list. This criterion divides the surviving tables into two “families,” each containing a characteristic decan list.

The star tables record that decans performed a certain action, in order, throughout the night. The action in question is commonly thought to be a star’s rising, but since the method of observation is never explicitly stated in or near the star tables, this is an assumption. Leitz hypothesised that the action could instead be the setting of stars.

This presentation describes a current research project investigating the observational methods which may have been used to construct the original decan lists. Some star names occur in both decan lists, others are unique to one. By comparing occurrences of two decans which are present in both families, it can be shown that the spacing between two such decans is often different in each family. This appears to be in conflict with the motion of real stars in the sky: if two stars rise with a certain time separation, that separation remains constant night after night unless the observer changes location significantly or a large number of years passes. However, if the events being observed are different in one family, the time separation between such decans can and does change. For example, stars that rise together do not necessarily set together.

The study investigates my recent proposal that one family of diagonal star tables records rising stars while the other, perhaps intended to be a complementary twin, records setting stars.

Liba Taub
Panel: “A Discussion of Thing Knowledge, a book by Davis Baird”
This panel will discuss the book Thing Knowledge, by Davis Baird. Participants include Davis Baird (Clark University), Joseph Pitt (Virginia Tech), Liba Taub (Whipple Museum of the History of Science and University of Cambridge), and Yaakov Zik (University of Haifa).

Todd Timberlake, Berry College
“Astronomy, History, and Computer Simulations: An Approach to Teaching the Nature of Science”
Introductory astronomy courses are among the most popular science courses taken by non-science majors in college. As a result, these courses represent a crucial opportunity to educate students about the nature of science. I have developed two courses that focus on teaching the nature of science through an exploration of the history of astronomy. One course examines the development of planetary astronomy from Aristotle to Isaac Newton. The other course follows changing notions about our place among the stars from Aristotle to Hubble. In both courses, students make frequent use of computer programs to simulate observations (the retrograde motion of Mars, parallax of the Moon, angular size of stars, etc) and to visualize theories (of planetary motion, the spatial distribution of stars, differential galactic rotation, etc). The goal of these activities is to help students see how empirical data constrains and tests theories, but at the same time theories help us interpret and explain empirical data. In addition, students learn that no theory stands alone: every purported test of a theory involves a host of other assumptions and theories that are taken for granted. One particularly important assumption that is often used in astronomy is that all objects within a given class will have similar properties, which relies critically on an appropriate method for classifying the objects. In addition, students explore ways in which non-empirical (aesthetic) criteria have been used by realists (but not phenomenalist) astronomers to choose between competing theories.

Course materials are available at:

Tom Williams
“Who Was Helping Who? A Century of Professional-Amateur Relationships: From Competition to Cooption to Cooperation”
Over the past century and a half, the relationship between professional and amateur astronomers has varied, from competition to cooption to full cooperation. While astronomical science has prospered to some degree under each of these approaches, amateur astronomy has not always enjoyed the same level of productivity in each. This paper will illustrate how each of these approaches influenced the evolution of variable star astronomy using the relationship between American Association of Variable Star Observers and Harvard College Observatory as a primary example, supplemented with illustrations from other sub-disciplines within astronomy.

Henry T. Zepeda, University of Oklahoma
“Spherical Trigonometry and His Medieval Commentators”
In book 1 of his Almagest, Ptolemy proves several trigonometric theorems that are necessary for his astronomy. Among these is the Menelaus theorem, which deals with the relationships of arcs on the surface of a sphere. This allowed the astronomer to convert between measurements along the celestial equator and the ecliptic, the path of the sun throughout the year. It was also used to find the rising times of different stars and planets at different latitudes, which was important not only for theoretical astronomy but also for the construction of horoscopes. Because this proposition also involved the use of compound ratios, which necessitates treating ratios as quantities that can be added and subtracted, proportion theory was necessary for its understanding. Because this proof was difficult and so fundamental to astronomy and astrology, medieval scholars wrote several treatises to explain it, and many commentaries and glosses on the Almagest treated this theorem at length. In my brief presentation, I will present the results of my doctoral research on dozens of previously unexamined medieval manuscripts containing the Almagest and commentaries upon it. I will give an overview of Ptolemy’s proof of the Menelaus theorem and its use in astronomy and astrology, and then I will discuss the medieval commentaries on the Almagest that expound upon the Menelaus theorem, the relationship of these commentaries to each other and to other works, and the proportion theory that these commentaries included.

Yaakov Zik and Giora Hon, University of Haifa
“Kepler’s Novel Method of Calculating the Eccentricity of the Sun”
The method of calculating the eccentricity of the Sun’s circle was based traditionally on the measurement of the time periods of the seasons as well as the length of the year. Tycho Brahe followed this tradition, but Johannes Kepler was not satisfied with Tycho’s determination of this parameter. In July 1600, in a letter to Herwart von Hohenburg, Kepler explained that in order to confirm his polyhedral hypothesis he needed accurate magnitudes of eccentricities and positional data. Kepler’s insistence on accurate observations was one of the reasons for his meeting with Tycho at Benatky Castle in April 1600. However, Tycho’s calculations of the planetary eccentricities and especially that of the Sun’s circle were not sufficiently accurate for Kepler. Moreover, he realized that, like Ptolemy and Copernicus, Tycho too accounted for the mean motion of the Sun and not for its true motion.

In 1604, in his Astronomiae pars optica, Kepler informed the reader that by the end of 1602 he had discovered a new method for measuring the apparent diameters of the Sun and Moon. Kepler’s optical method was sufficiently accurate to show variations in the apparent diameters of the Sun throughout the year. Measurements of the apparent solar diameter at the four extreme points (i.e., equinoxes and solstices), provided Kepler with data from which he could calculate the eccentricity of the Sun’s circle. We discuss this new optical method which helped Kepler determine with greater accuracy than ever before a crucial astronomical parameter—the eccentricity of the Sun’s circle.

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