various astronomy-related historical images

Biennial History of Astronomy Workshop - ND IX July 8 - 12, 2009

Abstracts (listed alphabetically)

Peter Abrahams, independent scholar
“An Overview of Automatic Telescopes”
Automatic (robotic) telescopes are a development of the past forty years. This does not refer to “remote operation,” where an astronomer can direct the telescope from a distance, but involves some level of machine intelligence, enabling a telescope to act without the direct initiative of an operator. An example is a telescope that senses weather, initiates, slews to a pre-programmed list of stars for photometry, then shuts down after the night; or a space-based gamma ray telescope that triggers a land-based optical telescope to slew to a gamma ray burst and observe the spectrum of the object. Precedents to these automatic telescopes include David Todd's “automatic device for photographing the solar corona,” and the hoax of Barnard's “automatic comet-finder.” This development of the capabilities of the telescope is an important milestone in the history of the telescope. It is hoped that historians will consider this as they contextualize the twentieth century, and that the participants in the technical evolution of telescope robotics will add their personal perspectives to the record.

Lindsay Bartolone, Adler Planetarium
“Completing the Copernican Revolution: Exploring the Boundaries of the Solar System”
The Sun and solar system move through a part of the galaxy known as the local interstellar medium, which is built up from material released from the stars of our galaxy.  The IBEX mission will chart the interaction between that medium and our sun’s heliosphere, mapping the extent of our solar system.

Barbara Becker, University of California, Irvine
“‘I am almost certain...’:  William Huggins and the First Attempts to Measure Stellar Motion in the Line of Sight”
When, in 1841, Christian Doppler proposed that the color of stars might be attributed to their motion along the line of sight, there was no way to put his controversial claim to the test.  This changed with the introduction of the spectroscope into the astronomer's toolkit in the 1860s. In February 1868, William Huggins (1824-1910) -- an amateur astronomer and pioneer in the emerging field of astrophysics -- became the first to apply Doppler's principle to the light of a star.  It was an effort fraught with overwhelming mensurational and interpretive difficulties.  Huggins's observatory notebook records bring new evidence to bear on both the steps he took to overcome these challenges and the rhetorical means by which he persuaded his contemporaries that he had, in fact, accomplished what he claimed. 

Trudy E. Bell, science journalist and independent scholar
“Meridian Circles and Transit Circles in Nineteenth-Century U.S. Observatories”
Most public, university, school, and private observatories in nineteenth-century America possessed not only a main telescope (the center of attraction), but also at least one specialized instrument of precision—most commonly, a transit instrument or meridian circle. These were costly instruments about which U.S. astronomers were proud, enumerating the size of their circles and the aperture of their main lens, which sometimes rivaled that of the observatory's main telescope. By 1840, U.S. observatories had adopted both British and German meridian instruments and soon also embraced German methods of quantifying errors pioneered by Bessel, Gauss, and others. By the early 1850s, U.S. astronomers had devised the "American method of transits," adapting telegraphic technology for electrically recording meridian transits; also by mid-century, at least one U.S. instrument-maker (William S. Young of Philadelphia) had begun building the precision mechanics of meridian/transit circles. By the 1880s, at least seventy-five transit circles or meridian circles had been installed in U.S. observatories, some of them ranking among the largest in the world (including the 8-inch Olcott Meridian Circle at Dudley Observatory in around 1856 and an 8.5-inch transit circle at the U.S. Naval Observatory in 1869). This paper will present (1) a tabular census of meridian instruments in nineteenth-century U.S. observatories, (2) an analysis of patterns of ownership, cost, and design, and (3) a discussion of the uses specific American astronomers made of them (such as determination of stellar and asteroid positions and proper motions; determinations of longitudes and local time; and teaching).

Chuck Beuter, Independent Scholar
“Exploring Historic Astronomical Sites in Second Life”
Information on how to effectively use social media tools in relation to history research is seemingly scarce.  Virtual worlds, such as Second Life, have more research available, but can be intimidating for those unfamiliar with them.  Join us for a practical look at what these tools have to offer and to explore new resources where you can continue your exploration, including a special look at Lord Rosse’s Leviathan and Galileo’s villa.

Marv Bolt, Adler Planetarium
“The Materials of Early Telescopes”
A combination of traditional and new curatorial tools yields new insights on the origins and evolution of the telescope.

Dayle L. Brown, author
“Simple Lenses”
These hands-on activities provide participants with the exciting chance to participate in a student’s discovery of how simple lenses can be combined to construct many optical devices such as Magnifiers, Cameras, Telescopes, and Projectors. “More than Magnifiers” (Cary Sneider, Alan Gould, et. al.) is one of the GEMS (Great Explorations in Math and Science) series created by the Lawrence Hall of Science, University of California at Berkeley. Emphasis will be given to the hands-on portions of the activities.  In “Magnifiers”, participants are provided with an important prerequisite for the following activities. The main objective is for the participants to understand how the curvature of a lens determines both its magnifying power and its field of view. In “Cameras”, participants will project images of a light bulb onto a piece of paper, just as a camera lens projects images onto film. They will explore the concept of “focal length” by observing and measuring using two different lenses.  In “Telescopes”, participants use a long focus lens and a short focus lens together as objective lens and eyepiece to make telescopes with different qualities.  In “Projectors”, participants will make table-top slide projectors using flashlights, lenses, and a slide; and discover the difference between a long-throw lens and a short-throw lens.  Handouts and all materials will be provided.

James Caplan, Observatoire Astronomique de Marseille-Provence
Telescopium: An Exhibition in Marseille”
The Marseille Observatory owns telescopes going back two and a half centuries. Since our small museum has recently been forced to close (temporarily), we decided to prepare a temporary exhibition on the history of the telescope in the nearby Natural History Museum. Many of the instruments in our museum are telescopes, and most of the others have telescopic parts; a dozen or so of our more prestigious objects (with the exception of clocks) will be on display. They illustrate a range of telescope types and the various uses for telescopes in astronomy (and geodesy, in the case of the Lenoir-Borda repeating circle used to measure the French meridian). Two meridian circles and a number of filar (and other) micrometers illustrate the role of telescopes in positional astronomy, while a 12-inch-diameter Short reflector and Foucault's 80-cm glass-mirror telescope (present only in photos—but the real thing is visible back at the observatory) illustrate other, more qualitative, aspects of astronomy such as searching for nebulae. The story line is rather narrowly the history of the telescope. We stray slightly from this path in mentioning some essential Galilean discoveries, and with a small didactic section covering some essential concepts of image formation and telescope optics. The talk will include my evaluation of the exhibition's success.

Roger Ceragioli, University of Arizona
“Beyond the Aspheric-Plate Camera: Bernhard Schmidt’s Final Invention”
Bernhard Schmidt’s fame rests on his revolutionary aspheric-plate camera of 1930. For the first time astronomers had a means of photographing large areas of the sky rapidly with extreme sharpness to the edge of the plate. They eagerly embraced the Schmidt camera from the mid 1930s, and with it changed the course of observational astronomy after World War II. Schmidt, alas, did not live to experience the fame this brought, but died prematurely in 1935.

The aspheric-plate camera was far from his only invention. The present talk will discuss Schmidt’s last design, an all-spherical camera, which has languished unrecognized for seventy years at the Hamburg Observatory in Germany where Schmidt worked. Its true nature was finally recognized by the present speaker in 2007. German colleagues disassembled it and confirmed his suspicion. The system is of a type called the “Buchroeder-Houghton” camera, a design until now thought to have been first devised by Dr. Richard A. Buchroeder in the United States in the 1960s.

The talk will briefly illustrate the optical design, discuss its significance in the development of twentieth-century astronomical optics, and how the author made his discovery.

Michael Crowe, University of Notre Dame, and Steven Dick, NASA
“Philosophy of Astronomy: Some Issues from the Extraterrestrial Life Debate,”
The research and writing that each of us did on the history of the extraterrestrial life debate revealed many issues in the philosophy of astronomy.   One major issue in the philosophy of science more generally is how and to what degree philosophical, especially metaphysical, claims should or do impinge on science itself.  In this context we shall briefly examine the major change that went on in the extraterrestrial life debate between 1543 and 1800, whereby the idea of a plurality of worlds went from being considered bizarre and unscientific to a broadly accepted idea that fit well with astronomy, metaphysics, and religion. As we tackled issues ranging from the canals of Mars to the search for planetary systems we also encountered many issues relevant to the nature, status, and objectivity of observations.  Whereas seventy-five years ago it was believed (for example in Hubble’s Realm of the Nebulae) that a sharp distinction should and could be drawn between theory and observation, by the 1960s and 1970s such authors as Hanson, Kuhn, and Feyerabend had raised problems for that distinction.  In areas where our research overlapped we did not always agree, for example, in our interpretation of the work of A. R. Wallace.  All these issues still resonate today in what might be called the philosophy of astrobiology.

David DeVorkin, National Air and Space Museum
Session on “Aspects of Astronomy during the Cold War”

David DeVorkin(2), National Air and Space Museum
“Consortia vs. National Facilities: C. P. Snow’s Two Cultures Revisited”

Steven J. Dick, NASA, and Michael J. Crowe, University of Notre Dame
Session on “Philosophy of Astronomy”
Fields such as philosophy of biology, philosophy of physics, and philosophy of technology are well developed, but astronomy has no such field, at least by that name.  This session explores what the scope of philosophy of astronomy would be, whether work has been done/is being done in the field under another name, what its relation is to the history of astronomy, whether it would be useful to cultivate such a field, and what the role of historians of astronomy might be in fostering philosophy of astronomy.

Steven J. Dick(2), NASA
“Inside NASA History: Personal Reminiscences”

Tom Fuller, Northwest Conservation
“Using Conservation Techniques to Answer Historical Questions”
The conservation and preservation of artifacts involves the knowledge of diverse materials. That knowledge can also provide valuable assistance with the interpretation of artifacts, as illustrated by a few examples now on display in the Adler Planetarium’s “Through the Looking Glass” telescopes exhibition.

George Gale, University of Missouri–Kansas City
“Wonder, Awe, and the Starry Sky Above: How the History of Astronomy Raises Issues for Philosophers”
Philosophy and astronomy have been entwined throughout their histories, mutually influencing one another, back and forth over the centuries. Yet, for whatever reason, philosophers have not turned their scrutiny upon this history, in order to examine astronomy as they have physics, biology, and, more recently, chemistry. The time has come. Astronomy offers a rich field for investigation, beginning with the most basic questions: What is astronomy? What kind of a science is it, what kind of a science has it been? Is it purely observational, or does it seek explanations? How does it differ from cosmology, now and through its history? Moving beyond these fundamental issues, one finds questions familiar from other sciences. Chief among them, both now and historically, is the question of the nature of the observation vs. theory interaction in astronomy. Does astronomy, now and in the past, present problems of observation/theory interaction peculiar unto itself? or is it little different from other physical sciences? When Bondi famously said “Never accept an observation until it’s been confirmed by theory,” he certainly implied something significant about observation/theory interactions in astronomy. Beyond this issue are many others of similar sort. A look at one final issue will complete the presentation: taxonomy and systematics are fundamental to any science. Does astronomy present any particular problems here? Cases which come immediately to mind involve the Hertzsprung-Russell classification and Hubble’s “tuning fork” scheme for galaxy taxonomy. As will be seen, this issue, just as the preceding pair, reveals the rich philosophical field provided by astronomy and its history.

Owen Gingerich, Harvard-Smithsonian Center for Astrophysics
“The Great Pluto Debate: What is a Planet?”
In a draft article for Social Studies of Science an anonymous author writes that the IAU’s planet definition committee “abdicated authority to science/nature in a move that tried to deny the social influence of scientific practice.  The purported cultural and historical work of the committee was limited to proposing a new nomenclature: the word ‘pluton’ to define a new class of planetary objects.”  Clearly an interpretive philosophical issue is at stake in this apparent put-down of the committee’s intended sensitivity to the cultural issues.  I shall present an insider’s view and critique of the events at the Prague IAU in August 2006 as the astronomers struggled to come to terms with a terminological issue.  Should they have attempted to define a culturally laden and long-evolving word, planet?

Owen Gingerich, Harvard-Smithsonian Center for Astrophysics
“Galileo’s Moon or Galilean Lunacy? A Modern Detective Story”
The printing history of Galileo’s hastily-prepared but epoch-making Starry Messenger is undoubtedly the most complex and fascinating story of scientific publishing.  In an edition of 550 copies, 24 missed having the lunar etchings printed.  Two years ago a distinguished German art historian described a copy of Galileo’s book in which the missing etchings were replaced by watercolor drawings, which he not only attributed to Galileo himself, but which he supposes were the original images from which the etched plates were made.  A detailed investigation shows that serious problems exist with this hypothesis.  Our piece of forensic detective work will demonstrate the collision between the methods of science and of art history.

Christopher Graney, Jefferson Community & Technical College
“The Universe of Stars as Revealed to Galileo by Sensory Experience with the Telescope”
Discussion of Galileo's telescopic discoveries and their role in the rise of the Copernican view of the universe are typically limited to those involving solar system objects—the moon's craters, sun's spots, Jupiter's moons, Venus's phases. But Galileo observed the stars telescopically as well. He considered them suns (essentially identical to the sun in size) whose apparent sizes he could measure and whose distances he could calculate. This talk will begin with a brief overview of these observations and ideas. It will then touch on how these could be used to support Copernican ideas (through counts of numbers of naked eye stars) as well as undermine them (through lack of detectable annual parallax). The bulk of the talk will be a discussion of exactly what sort of universe is allowed by Galileo's observations of the stars — what kind of model of the universe is required in light of the data available to Galileo (in light of sensory experience, as he might say) — and why.

Robert J. Havlik, University of Notre Dame
“Astronomy at the Fair: An Untapped Source on the History of Popular Astronomy”
World’s fairs are periodic extravaganzas celebrating the advancement of human cultures and current public interests in the heritage of various scientific and liberal-arts subjects. Astronomy has played a part in all world’s fairs, from the application of photography, through the development of the application of physical instruments to explore our universe, to modern space science and exploration. A few fairs have even made astronomy or space science a major theme for the fair. In the majority of fairs, however, astronomy exhibits and advancements have been only a quiet presence. Newly available collections of original world’s fair catalogs and documents, supplemented by the availability of new information on the Internet, now allows us to examine these fairs more closely for their contribution to our understanding of the history of astronomy. This paper and accompanying slides are a sample of some of the gems found in just one fair, the World’s Columbian Exposition of 1893 in Chicago. In the process of research, I was also able to solve a mystery of why the Lick Observatory exhibit was mixed in with the California Department of Education Kindergarten exhibit. Even more startling was the discovery of a connection of the U.S. government’s astronomy and observatory exhibits to the University of Notre Dame.

R. Kent Honeycutt, Indiana University
“Automatic Telescopes at Indiana University”
The development of systems and techniques for the automation of telescopes and observatories is briefly reviewed, with an emphasis on work at Indiana University in the 1970–80's. Automation has affected the way observational astronomers do their work, the kinds of research problems addressed, and how collaborations are arranged and conducted. The various types and levels of automation are examined. Each kind of automation has strengths and weaknesses that govern its suitability to different categories of research projects.

Don Howard, University of Notre Dame
“‘But this is wondrous strange!’ Constructing an Agenda for the Philosophy of Astronomy”
This talk aims to sketch an agenda for a new field of the philosophy of astronomy by way of exemplars – topics within astronomy that either inform or are informed by issues in the philosophy of science more generally. Among the specific topics to be addressed are: (1) The personal equation and objectivity; (2) Bootstrapping and the determination of the Hubble constant; (3) Neptune/Vulcan and Duhem’s “bon sens”; (4) Data analysis and “experimental practice” in astronomy.

Rudi Lindner, University of Michigan
 “R. R. McMath as an Engine of Change in American Astronomy”
Robert McMath began his career as a professional engineer and amateur astronomer.  The building, and success, of the McMath-Hulbert  Observatory, his work during World War II, and his diplomatic skills, raised his status within the communities of astronomy and the federal government.  This talk discussed McMath's role as middle-man between these communities during the Cold War.

Jordan D. Marché II, Lakeland College
“Popularization and Pedagogy: Insights from Early Nineteenth-Century Textbooks”
A comparative study of several leading astronomy-related textbooks, published (or republished) by American and British authors, reveals a number of similarities. Among these works, the emphasis is almost entirely practical, with lessons devoted to determination of latitudes, longitudes, and observations of eclipses. In a single-edition work, the audience was regarded as children “in very early life” and “the student in his progress to the higher departments of science.”

While the significance of these texts is difficult to gauge, the number of editions printed, or of copies still preserved, offers evidence of their adoption. This data must be viewed cautiously, however, as copies of the single-edition work are almost as numerous as the total copies of another, multi-edition work (where earlier editions were presumably discarded).

What these texts have most in common is an emphasis upon the foundational relationship between astronomy and geography. In one multi-edition work, astronomy is termed “preparatory to ancient and modern geography,” suggesting an application towards study of the classics. Evidence for the longevity of this linkage can be traced to other elementary texts published as late as 1847.

Astronomy and geography were seemingly united before or during the Enlightenment, a process reflecting the Newtonian revolution connecting the heavens and Earth. Evidence from textbooks concerning the linkages of these disciplines implies that astronomy did not break away from geography, and itself become a more theoretical, independent discipline, until sometime after the early decades of the nineteenth century.

Michael Michaud, independent scholar
“It’s about the Evidence”
When the best physical scientists study the universe, they report it as it is, not as they wish it would be. Yet some do not observe that standard when they predict the nature of an extraterrestrial civilization, or the consequences of our coming into contact with such an alien society. Too often, we get opinions instead of systematic analyses drawing on the only data base we have— human history and behavior. Many authors have been very selective in choosing analogies from the human past; they have excluded or ignored much of the evidence from our own history, apparently because it clashes with their preferred outcomes.

It is difficult to exclude emotions and preferences from this speculative debate. Nonetheless, we should seize the opportunities we have to introduce greater objectivity. Historians, with their knowledge of and perspective on human behavior, can make a valuable contribution—if they observe the standards of the best physical science, reporting our conduct as it actually was.

Matt Stanley, New York University
“Eddington’s Worldview and Eddington’s Science as a Problem in Philosophy of Astronomy”
Eddington, as one of the most influential astrophysicists of the twentieth century, has left a peculiarly two-pronged legacy.  On one hand we have his theoretical work on stellar models, which was extremely fruitful.  On the other hand we have his attempts at unified cosmological theories, which was a spectacular failure.  How do we get two such divergent projects out of the same person and, presumably, the same worldview? While trying to make sense of this we will have the chance to grapple with some possible elements of the philosophy of astronomy: Eddington’s work takes us through astronomical methodologies, the relations of observation and theory, and the goals of astronomy. 

Voula Saridakis, Lake Forest College
“Urania’s ‘Progress’: Women’s Shifting Roles in Observational Astronomy from the Late Seventeenth to Early Nineteenth Centuries”
During the time period between the work of Elisabetha Hevelius in the late seventeenth century and Margaret Bryan in the early nineteenth century, the telescope and traditional measuring instruments became increasingly sophisticated. The compilation and dissemination of astronomical knowledge also grew, as did the wider popularization of both astronomy and instrumentation.

In this work-in-progress, I examine the astronomical work and shifting roles of several women in this time period. I briefly begin with Elisabetha, Johannes Hevelius’s wife and assistant, who helped him observe and measure the night sky using positional measuring instruments. Then I describe Caroline Herschel’s extensive use (and construction of) telescopes and instrumentation. This study ends with Margaret Bryan (b. ca. 1760) whose image (along with her two daughters) appears on the frontispiece of her A Compendious System of Astronomy (1797). She taught astronomy and natural philosophy to girls at her school in Blackheath, London, from 1795 to 1806, and opened another school in central London in 1815, the same year she published her An Astronomical and Geographical Class Book for Schools. I demonstrate (a topic worth pursuing in greater depth and detail) how the roles of women astronomers were tied to the extent to which they used their telescopes and measuring instruments, and how women’s work as astronomers shifted among assistant, observer, and educator in this period of approximately 150 years.

Jefferson Sauter, James Cook University (co-author and presenter); Irakli Simonia, Ilia Chavchavadze University and James Cook University; F. Richard Stephenson, University of Durham and James Cook University; Wayne Orchiston, James Cook University
“Historical Astronomy of the Caucasus: The Sources from the Republic of Georgia”
A newly-initiated research effort at the Centre for Astronomy, James Cook University, aims to provide the first known large-scale survey and analysis of Georgian astronomical manuscripts within the context of cultural astronomy and applied historical astronomy. Premodern Georgian astronomy remains a topic underserved by historians and scientists as well as by scholars of Georgia (“kartvelologists”), despite calls from Georgian and Russian academics for further investigation. Yet—at least with respect to the written sources from the 8th through the 19th centuries—scores of Georgian manuscripts are extant on various themes in cultural and historical astronomy. In other words, for various reasons the history of premodern Georgian astronomy has not received the attention it merits. In this presentation, we briefly survey what scholars already been uncovered of Georgian astronomical texts and practice, and address the written sources themselves. The focus of our project is generally limited to one group of these astronomical texts—namely, those relating specifically to the Sun and solar phenomena. Such texts include those discussing sunsets and sunrises; the motion of the Sun along the ecliptic; eclipses and halos; and the Sun and solar phenomena in the context of Georgian calendars and time-keeping devices. We conclude by describing the extent to which better knowledge of the astronomical sources from this part of the world, is highly expected not only to illuminate how the Georgians interpreted and understood the heavens, but also to yield valuable observational data for applied historical astronomy.

Robert Smith, University of Alberta
“A Gift of the Cold War: The Making of Space Astronomy”

Michael Smutko, Adler Planetarium and Northwestern University
“Un-twinkling the Stars”
Atmospheric turbulence frustrated astronomers even before Huygens first described the problem in 1659.  I will discuss the theory and construction of adaptive optics (AO) systems that remove the effects of atmospheric turbulence in real time from ground-based telescopes, and present results from modern AO-equipped telescopes that are achieving image resolutions superior to their space-based counterparts.

Mark SubbaRao, Adler Planetarium
“As Stars Fade in Bright Skies, Virtual Telescopes Reopen the Heavens”
While light pollution makes it possible to view only a handful of stars, powerful computer visualization technologies enable new ways to experience the heavens. These programs make it possible to see data in colors beyond the visible, into radio and even X-ray wavelengths.  Most systems also allow people to view the sky collectively and share their reflections in user-based communities.  I will explore the state of these virtual telescopes and discuss them as the latest tools to allow people to view and understand the heavens.

Craig B. Waff, Air Force Research Laboratory History Office
Session on “Episodes in the Nineteenth-Century Popularization of Astronomy: Textbooks, Lecture Tours, and World’s Fairs”
Taking note that one of the goals of the International Year of Astronomy is to increase the public’s awareness of astronomy’s rich heritage, we explore in this session three different means by which knowledge of astronomy and its history was promoted among the public during the nineteenth century. Jordan D. Marché II (“Popularization and Pedagogy: Insights from Early Nineteenth-Century Textbooks”), as part of a comparative study of several leading astronomy-related textbooks published in the early nineteenth century, discusses the foundational relationship between astronomy and geography that is emphasized in these early texts. Craig B. Waff (“Orator to the Stars: An Investigation of the Scope, Content, Style, and Influence of Ormsby MacKnight Mitchel’s Public Astronomical Lecturing Activity [1842–1860]”) reconstructs the extensive lecture tours of the Cincinnati Observatory founder and director and discusses the impact of his lectures on not only the mid-nineteenth-century American public, but also the development of astronomy in the United States during the same period. Robert J. Havlik (“Astronomy at the Fair: An Untapped Source on the History of Popular Astronomy”) discusses the role astronomy has played in world’s fairs, exploring in particular the World’s Columbian Exposition held in Chicago in 1893.

Craig B. Waff(2), Air Force Research Laboratory History Office
“Orator to the Stars: An Investigation of the Scope, Content, Style, and Influence of Ormsby MacKnight Mitchel’s Public Astronomical Lecturing Activity (1842–1860)”
Ormsby MacKnight Mitchel presented numerous popular series of lectures on astronomy in various American cities virtually every year from the winter of 1842 to the fall of 1860. Although most publications concerning Mitchel have mentioned his lecturing, their authors have provided few details. In this paper, I present preliminary findings from an investigation of: (1) Mitchel’s motivations for undertaking such activity; (2) the scope of his lecturing activity (at last count, at least fifty-three separate speaking engagements, each ranging from one to six lectures); (3) the sponsors of and audiences for his lectures and the venues where he presented them (in at least twenty separate cities); (4) the content of his lectures; (5) the characteristics of his speaking style; and (6) the influence, if any, of his lectures on the development of astronomy in the United States. My conclusions are based not only on consultation of traditional source material (such as published papers, unpublished letters, and Mitchel’s published books of lectures), but also employment of an innovative research technique—an aggressive search of recently available searchable online databases of historical newspapers to identify lectures he gave, as well as to gain transcripts of his actual words and reporters’ accounts of audience response.

Yaakov Zik and Giora Hon, University of Haifa
The introduction of the telescope as a scientific instrument into astronomy was of signal importance for the development of modern science. The received view holds that the first spyglass was assembled without any theoretical understanding how it magnifies. Artisans who had the first telescopes which magnified 3 or 4 times knew nothing—so the historical argument goes—of the principles by which this instrument worked and never managed to improve their magnifying power. However, Galileo who first used the instrument as a scientific tool did improve the power of magnification up to 30 times. It is therefore even more intriguing to hold that Galileo increased the power of magnification on no theoretical basis since the traditional knowledge of the optics of his day was not suitable to the analysis of system of lenses.

We offer an alternative view on this puzzling situation. Our interpretation rests essentially on the fact that Galileo was the first scholar to apply successfully the telescope to astronomical observations. A working astronomical telescope is a complex optical device consisting of a tube, lenses, and aperture stops. In order to turn the telescope into a high-quality magnifying device, one has to find solutions to problems such as: How does the telescope magnify? Can one reduce image defects? How can one improve (in modern terms) resolution? And how does one produce adequate lenses? We argue that these problems cannot be solved by accidentally stumbling upon a complex procedure.

The telescope magnifies distant objects by presenting them to the eye in a greater angle than the angle subtended by the naked eye. This fundamental ratio between visual angles was known to opticians and mathematicians, among them Galileo, from the application of surveying instruments for measuring the height of remote objects using a mirror. We submit that the theory of the telescope was developed through analogical reasoning based on the phenomenon of reflection in mirrors which was extended to refraction in lenses. In spite of the fact that no adequate theory of refraction was available, Galileo could have applied such an analogy to help understand the working of the telescope and thus improve its magnification, making it a revolutionary scientific instrument.

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