This paper presents an analysis of the systematic astronomical observations performed by Muḥyī al-Dīn al-Maghribī at the Maragha observatory between 1262 and 1274 AD. In a treatise entitled Talkhīṣ al-majisṭī, preserved in a unique copy at Leiden, Universiteitsbibliotheek, Muḥyī al-Dīn explains his observations and measurements of the Sun, the Moon, the superior planets, and eight reference stars. His measurements of the meridian altitudes of the Sun, the superior planets, and the eight bright stars were made using the mural quadrant of (...) the observatory, and the times of their meridian transit using a water clock. The mean absolute error in the meridian altitudes of the Sun is ~ 3.1′, of the superior planets ~ 4.6′, and of the eight fixed stars ~ 6.2′. The clepsydras used by Muḥyī al-Dīn could apparently fix time intervals with a precision of ± 5 min. His estimation of the magnitudes of three lunar eclipses observed in Maragha in 1262, 1270, and 1274 AD is in close agreement with modern data. (shrink)

An Andalusian tradition of zījes seems to have been predominant in the Maghrib due to the popularity of the zīj of Ibn Is[hdotu]āq al-Tūnisī and derived texts compiled in the fourteenth century. This tradition computed sidereal planetary longitudes and allowed the calculation of tropical longitudes by using trepidation tables based on models designed in al-Andalus by Abū Is[hdotu]āq ibn al-Zarqālluh. This tradition also used Ibn al-Zarqālluh's model to calculate the obliquity of the ecliptic, which implied that this angle had a (...) cyclical period of oscillation between a maximum of 23;53° and a minimum of 23;33°: after reaching this minimum value the obliquity of the ecliptic was bound to increase. This paper argues that some new Maghribi sources give information on observations made in the Maghrib in the fourteenth and beginning of the fifteenth centuries that imply that precession had increased beyond the limits allowed by the Zarqāllian trepidation theory, while the obliquity of the ecliptic had diminished below the level accepted by astronomers who followed Ibn al-Zarqālluh. This explains the introduction in the Maghrib of Eastern zījes, which computed directly tropical longitudes and did not accept the cyclical variation of the obliquity. Information about observations of dawn and twilight made both in Egypt and in the Maghrib in the fourteenth and fifteenth centuries is also presented. (shrink)

This paper considers the role of the doctrine of providence, and particularly the distinction between general and special providence, in the interpretation of astronomical observations in the sixteenth century, with particular reference to the discussion of the 1572 nova by Lutheran astronomers. It suggests that the essential difference between the events of special providence and those of general providence could be used to legitimate observations which contradicted accepted Aristotelian physics. The decision that the underlying explanatory system must be revised thus (...) required a theological shift as well as contradiction by observation. (shrink)

ABSTRACT This article is devoted to a thirteenth-century Latin text on how to construct, set up, and use a version of the so-called armillary instrument (instrumentum armillarum), which was first described in Ptolemy’s Almagest as a tool for measuring ecliptic coordinates. Written in 1264 by Guillaume des Moustiers, bishop of Laon, this hitherto unstudied Tractatus super armillas survives in a single manuscript, where it is accompanied by a copious set of glosses. The text and its glosses jointly offer an unusually (...) detailed account of the instrument’s material aspects and methods of assembly. In addition, they reflect a keen awareness of the potential sources of error that may arise in the context of astronomical observation, while making suggestions on how these errors may be minimized or avoided. The Tractatus super armillas accordingly is a valuable source on the observational side of medieval European astronomy, which has often been minimized in modern historical accounts. (shrink)

ABSTRACT Our discussion of Niccolò Tornioli's The Astronomers questions some of the traditional identifications of its characters, although we cannot claim to have solved these figures’ identities and several remain a mystery. We do present new iconographic interpretations of particular scientific instruments, diagrams, and natural phenomena in the canvas. These novel readings occasionally remain conjectural in part because Tornioli represents these entities in a way that makes it clear that he did not fully comprehend them. The errors and obscurities in (...) Tornioli’s painting lead us to two conclusions. First, that his erudite patron Virgilio Spada was unlikely to have been involved in the definition of the painting’s iconographies, as he would have objected to Tornioli’s crass mistakes and obscure imagery. Second, that these errors and indistinct details should be taken at face value, insofar as they accentuate the difficulties of astronomical observation. Beyond highlighting these challenges, we argue that the painting also visualizes techniques for countering them. Specifically, the canvas would have focused early modern observers’ attention on the edifying powers of civil conversations and communal observations with scientific instruments as well as images—including diagrams, celestial maps, and paintings. (shrink)

This paper examines the interrelations between astronomical images of nebulae and their observation. In particular, using the case of the ‘Great Spiral’ , we follow this nebula beginning with its discovery and first sketch made by the third Earl of Rosse in 1845, to giving an account, using archival sources, of exactly how other images of the same object were produced over the years and stabilized within the record books of the Rosse project. It will be found that a (...) particular ‘procedure’ was employed using ‘working images’ that interacted with descriptions, other images and the telescopic object itself. This stabilized not only some set of standard images of the object, but also a very potent conception of spirality as well, i.e. as a ‘normal form’. Finally, two cases will be contrasted, one being George Bond's application of this spiral conception to the nebula in Orion, and the other Wilhelm Tempel's rejection of the spiral form in M51. (shrink)

The ArgumentIt is often assumed that all sciences travel the path of increasing precision and quantification. It is also assumed that such processes transcend the boundaries of rival scientific disciplines. The history of the personal equation has been cited as an example: the “personal equation” was the name given by astronomers after Bessel to the differences in measured transit times recorded by observers in the same situation. Later in the nineteenth century Wilhelm Wundt used this phenomenon as a type for (...) his experiments on reaction times. For historians of psychology, this has been taken to be an exemplary case where quantified laboratory science rescued astronomy by showing that this was really a psychological phenomenon measurable only in complication experiments. This paper challenges this story. Astronomers neither ignored, nor despaired of, the personality problem. Instead, the managers of the great observatories developed a new chronometric regime of vigilant surveillance of subordinate observers. The astronomers' solution was thus intimately connected with social and material changes in their way of life: a division of labor in the observatories, a network of observing sites, a mechanization of observation. The paper documents these changes and then presents a study of one case where managers, amateurs, and psychologists clashed for authority over the personality problem. Measurement is given its meaning when situated in specific contexts of styles of work and institutions. Disciplines give meanings to values, and often resist attempts by others to redefine these meanings or to gain authority over measurement. Quantification is not a self-evident nor inevitable process in science's history, but possesses a remarkable cultural history of its own. (shrink)

This article presents evidence that an anonymous publication of 1573, aLetter sent by a gentleman of England [concerning …] the myraculous starre nowe shyning, was written by Thomas Digges, England's first Copernican. It tells the story of how it arose out of research commissioned by Elizabeth I's privy counsellors in response to the conventional argument of Jean Gosselin, librarian to Henri III of France, that the star was a comet which presaged wars. The text is significant because it seems to (...) contain the observations and opinions that Digges held before he completed his other astronomical treatise, the groundbreakingAlae seu scalae mathematicae. It also casts some light on the development of Digges's radical and puritan views about the star, Copernican astronomy, the infinity of the universe and a belief that the ‘latter days’ of the world had arrived. (shrink)

A reanalysis of the eight astronomical images that Johann Adam Schall von Bell incorporated in the first Chinese treatise on the telescope to illustrate the telescopic discoveries made by Galileo Galilei shows that they were borrowed from the works on telescopic astronomy by Galileo Galilei and Johann Georg Locher, a student of Christopher Scheiner. Except minor changes to both Galileo’s illustrations of the telescopic view of the moon and nebulae and Locher’s illustration of sunspots, Locher’s images about the phases of (...) Venus and Jovian satellites were redrawn presumably to convey a clearer commitment to Tycho Brahe’s system of the world and most of the contents in Locher’s image of Saturn was replaced by Schall’s own observation. These changes seem to be the result of two important factors that confined the transcultural transmission of astronomical knowledge from Europe to China through the Jesuits in the seventeenth century, namely the official standpoint of the Catholic Church on the ongoing cosmological issues and the cultural tradition of Chinese astronomy. (shrink)

A reanalysis of the eight astronomical images that Johann Adam Schall von Bell incorporated in the first Chinese treatise on the telescope to illustrate the telescopic discoveries made by Galileo Galilei shows that they were borrowed from the works on telescopic astronomy by Galileo Galilei and Johann Georg Locher, a student of Christopher Scheiner. Except minor changes to both Galileo’s illustrations of the telescopic view of the moon and nebulae and Locher’s illustration of sunspots, Locher’s images about the phases of (...) Venus and Jovian satellites were redrawn presumably to convey a clearer commitment to Tycho Brahe’s system of the world and most of the contents in Locher’s image of Saturn was replaced by Schall’s own observation. These changes seem to be the result of two important factors that confined the transcultural transmission of astronomical knowledge from Europe to China through the Jesuits in the seventeenth century, namely the official standpoint of the Catholic Church on the ongoing cosmological issues and the cultural tradition of Chinese astronomy. (shrink)

In the ancient civilizations, the sky has been observed in order to understand the motions of the celestial bodies above the horizon. The study of faiths and practices dealing with the sky in the past has been attributed to the sun, the moon, and the prominent stars. The alignment and orientation of constructions to significant celestial objects were a common practice. The orientation was an important component of the religious structure design. Religious buildings often have an intentional orientation to fix (...) the praying direction. In Islam, a sacred direction towards Kaaba located in the courtyard in the Sacred Mosque in Mecca has been used for praying and fulfilling varied ritual tasks. Therefore, the mosques had then to orientate towards the Qibla direction, being designated by a focal niche in the Qibla-wall, wherever they were built on Earth. In this study, the orientations of the historical Grand mosques in Turkey are surveyed with regard to the folk astronomy derived from pre-Islamic Arabian sources, early traditions of the Islamic period, and geometric-trigonometric computation in mathematical astronomy inherited and developed mostly from Greek sources according to the Islamic view of the World geography. (shrink)

BM 76829, a fragment from the mid-section of a small tablet from Sippar in Late Babylonian script, preserves what remains of two new unparalleled pieces from the cuneiform astronomical repertoire relating to the zodiac. The text on the obverse assigns numerical values to sectors assigned to zodiacal signs, while the text on the reverse seems to relate zodiacal signs with specific days or intervals of days. The system used on the obverse also presents a new way of representing the concept (...) of numerical ‘zero’ in cuneiform, and for the first time in cuneiform, a system for dividing the horizon into six arcs in the east and six arcs in the west akin to that used in the Astronomical Book of Enoch. Both the obverse and the reverse may describe the periodical courses of the sun and moon, in a similar way to what is found in astronomical texts from Qumran, thus adding to our knowledge of the scientific relationship between the two cultures. (shrink)

This unique volume by two renowned astrophotographers unveils the science and history behind 100 of the most significant astronomical images of all time. The authors have carefully selected their list of images from across time and technology to bring to the reader the most relevant photographic images spanning all eras of modern astronomical history. Based on scientific evidence today we have a basic notion of how Earth and the universe came to be. The road to this knowledge was paved with (...) 175 years of astronomical images acquired by the coupling of two revolutionary technologies - the camera and telescope. With ingenuity and determination humankind would quickly embrace these technologies to tell the story of the cosmos and unravel its mysteries. This book presents in pictures and words a photographic chronology of our aspiration to understand the universe. From the first fledgling attempts to photograph the Moon, planets, and stars to the marvels of orbiting observatories that record the cosmos at energies beyond the range of human vision, astronomers have always relied on images to "break through" to the next level of understanding. A subset of these breakthrough images has profound significance in documenting some of the greatest milestones in modern astronomy. (shrink)

The Astronomical Diaries are a unique corpus of documents from Babylon containing daily observations of celestial and terrestrial phenomena in the last half millennium before the Common Era. They provide direct information on how Babylonian scholars conducted scientific research and viewed political, economic, and religious events of their time—in other words, how they experienced their era. The book under review is a good introduction to this corpus.

From the early ninth century until about eight centuries later, the Middle East witnessed a series of both simple and systematic astronomical observations for the purpose of testing contemporary astronomical tables and deriving the fundamental solar, lunar, and planetary parameters. Of them, the extensive observations of lunar eclipses available before 1000 AD for testing the ephemeredes computed from the astronomical tables are in a relatively sharp contrast to the twelve lunar observations that are pertained to the four extant accounts of (...) the measurements of the basic parameters of Ptolemaic lunar model. The last of them are Taqī al-Dīn Muḥammad b. Ma‘rūf’s trio of lunar eclipses observed from Istanbul, Cairo, and Thessalonica in 1576–1577 and documented in chapter 2 of book 5 of his famous work, Sidrat muntaha al-afkar fī malakūt al-falak al-dawwār. In this article, we provide a detailed analysis of the accuracy of his solar and lunar observations. (shrink)

Today we are all familiar with the iconic pictures of the nebulae produced by the Hubble Space Telescope’s digital cameras. But there was a time, before the successful application of photography to the heavens, in which scientists had to rely on handmade drawings of these mysterious phenomena. Observing by Hand sheds entirely new light on the ways in which the production and reception of handdrawn images of the nebulae in the nineteenth century contributed to astronomical observation. Omar W. Nasim (...) investigates hundreds of unpublished observing books and paper records from six nineteenth-century observers of the nebulae: Sir John Herschel; William Parsons, the third Earl of Rosse; William Lassell; Ebenezer Porter Mason; Ernst Wilhelm Leberecht Tempel; and George Phillips Bond. Nasim focuses on the ways in which these observers created and employed their drawings in data-driven procedures, from their choices of artistic materials and techniques to their practices and scientific observation. He examines the ways in which the act of drawing complemented the acts of seeing and knowing, as well as the ways that making pictures was connected to the production of scientific knowledge. An impeccably researched, carefully crafted, and beautifully illustrated piece of historical work, Observing by Hand will delight historians of science, art, and the book, as well as astronomers and philosophers. (shrink)

Paolo Beni da Gubbio (1553-1625) has been studied almost exclusively for his literary and rhetorical production. However, he finds an important place among the scholars of the Renaissance who developed a novel reading of Plato as an alternative to the predominant exegesis of Ficino and his followers. His writings represent a prime example of the interplay between exegetical discussions (both of literary and philosophical texts) and the emerging sciences. In the unpublished part of his commentary on Plato’s "Timaeus", Beni discusses (...) Platonic natural philosophy – cosmology in particular – in the light of the interpretations of other authors as well as the new scientific theories, mostly in relation to the Paduan scientific circles. From Galileo’s correspondence with Giovan Battista Manso, we know that Beni weas well-informed about Galileo’s astronomical observations and discoveries at the beginning of 1610, which were soon published thereafter in the "Sidereus Nuncius". Further, we have information concerning Beni’s active role in the circulation of these observations. We wish to cast new light on the reception of these novelties by an advocate of the classical tradition such as Beni. Beni’s praise of the new discoveries is testified by his unedited commentary to the Ciceronian "Dream of Scipio" (1610-15), in which he criticizes the Aristiotelian cosmological model, referring to the newly invented telescope and referring to Galileo’s astronomical observations. Echoes of new scientific and cosmological theories appear also in Beni’s commentaries on Tasso’s "Delivered Jerusalem". (shrink)

Summary Although by the mid-eighteenth century colonial American makers of mathematical instruments were producing many of the scientific instruments required in the British Colonies of North America for surveying and navigation, it was not until after the first quarter of the nineteenth century that American makers had the capability to produce sophisticated precision optical instruments for astronomy and microscopy. Until then, these had to be imported from overseas, chiefly England, at considerable cost and after long delays. Included among them were (...) historically important instruments required for establishing provincial and territorial boundaries, and for making astronomical observations. Although generally treated with the utmost care while in use, eventually one after another was misplaced, lost, destroyed by fire, or, in one instance, carefully hidden away then forgotten until it was discovered more than a century later. (shrink)

The beginnings of photographic astronomy in Sweden are taken as a case study of the incorporation of a new scientific technology. The introduction of photography during the late nineteenth century profoundly changed the way astronomers worked. Observational material became more mobile; photographic plates could be examined at a later date or transported to another location. Photography was presented in a rhetorical language, making it a truly objective way of observing the sky. The new technology was developed at the leading observatories, (...) and was imported into countries such as Sweden through a network of scientific communication. (shrink)

The mechanism of stellar aberration was explained and formulated by Bradley in terms of the existence of a unique reference frame for light propagation. However, Einstein's denial of the existence of such a frame appears to undermine Bradley's interpretation of the phenomenon. It is suggested that the recent evidence for a cosmologically-based inertial reference frame provides a new physical basis for Bradley's explanation in a manner consistent with the requirements of special relativity. It is shown that a “delay” effect is (...) also involved in our observation of the direction of nearby sources, and that the aberration and delay effects exactly compensate for nearby sources comoving with a terrestrial observer. (shrink)

It is customary to distinguish experimental from purely observational sciences. The former include physics and molecular biology, the latter astronomy and palaeontology. Experiments involve actively intervening in the course of nature, as opposed to observing events that would have happened anyway. When a molecular biologist inserts viral DNA into a bacterium in his laboratory, this is an experiment; but when an astronomer points his telescope at the heavens, this is an observation. Without the biologist’s handiwork the bacterium would never (...) have contained foreign DNA; but the planets would have continued orbiting the sun whether or not the astronomer had directed his telescope skyward. The observational/experimental distinction would probably be difficult to make precise 1, as the notion of an ‘intervention’ is not easily defined, but it is intuitively fairly clear, and is frequently invoked by scientists and historians of science. Experimentation, or ‘putting questions to nature’, is often cited as a hallmark of the modern scientific method, something that permitted the enormous advances of the last 350 years. And it is sometimes said that the social sciences lag behind the natural because controlled experiments cannot be done so readily in the former. Moreover in certain sciences, e.g. epidemiology, students are explicitly taught that experimental data is preferable to observational data, particularly for doing causal inference. So the distinction between observational and experimental science has quite wide currency, and is often regarded as methodologically significant. Surprisingly, mainstream philosophy of science has had rather little to say about the observational/experimental distinction. 2 For example, discussions of confirmation usually invoke a notion of ‘evidence’, to be contrasted with ‘theory’ or ‘hypothesis’; the aim is to understand how the evidence bears on the hypothesis. But whether this ‘evidence’ comes from observation or experiment generally plays no role in the discussion; this is true …. (shrink)

In this paper, we discuss Babylonian observations of a “massing of the planets” reported in two Astronomical Diaries, BM 32562 and BM 46051. This extremely rare astronomical phenomenon was observed in Babylon between 20 and 30 March 185 BC shortly before sunrise when all five planets were simultaneously visible for about 10 to 15 min close to the horizon in the eastern morning sky. These two observational texts are not only interesting as records of an extremely rare planetary configuration, but (...) also because the observers appear to be confused by the presence of all planets simultaneously and mix them up in their reports, and the two reports of the same observations are so different that we are forced to conclude that they were carried out by two different observers. There is an additional astronomical event which makes this planetary configuration even more unique: the exact conjunction of the planets Mars and Jupiter in the afternoon of 25 March 185 BC. An exact conjunction, where two planets are so close together that they appear as one object in the sky, is also extremely rare. Although this exact conjunction between Mars and Jupiter occurred during the day so that it was not observable, it was correctly predicted by the Babylonian scholars: a remarkable achievement and a nice illustration of their astronomical craftsmanship. Finally, our study clearly exposes one of the limitations of Babylonian naked-eye astronomy. When first appearances of the planets Mercury, Mars and Saturn are expected around the same date, it is nearly impossible to correctly identify them because their expected positions are only approximately known while they have about the same visual magnitude so that they become visible at about the same altitude above the horizon. (shrink)

In the century between the creation of the first large, European astronomical observatory by Tycho Brahe in the 1580s and the national observatories of France and England in the 1660–1670s, astronomers constructed ever more sets of tables, derived from various geometrical and physical models, to compute planetary positions. But how were these tables to be evaluated? What level of precision or accuracy should be expected from mathematical astronomy? In 1644, the Stetin astronomer and calendar-maker Lorenz Eichstadt published a new set (...) of tables, mostly cobbled together from earlier tables, which include a running commentary on how his tables might be expected to match ‘observed’ planetary positions. His earlier works also often display a rhetoric of ‘exactitude’ and ‘error’. Eichstadt thus offers a case study of explicit discussions of ‘precision’ in mid-seventeenth astronomy. Although some tables could generate positions to arcseconds, Eichstadt argued that a regime of five arcminutes should be enough for most table users who were, presumably, computing horoscopes. (shrink)

Centring on John Flamsteed, the first Astronomer Royal, this paper investigates the ways in which astronomers of the late seventeenth century worked to build and maintain their reputations by demonstrating, for their peers and for posterity, their proficiency in managing visual technologies. By looking at his correspondence and by offering a graphic and textual analysis of the preface to his posthumousHistoria Coelestis Britannica, I argue that Flamsteed based the legitimacy of his life's work on his capacity to serve as a (...) skilful astronomer who could coordinate the production and proper use of astronomical sighting instruments. Technological advances in astrometry were, for Flamsteed, a necessary but not a sufficient condition for the advancement of astronomy. Technological resources needed to be used by the right person. The work of the skilful astronomer was a necessary precondition for the mobilization and proper management of astronomical technologies. Flamsteed's understanding of the astronomer as a skilled actor importantly shifted the emphasis in precision astronomical work away from the individual observer's ability to see well and toward the astronomer's ability to ensure that instruments guaranteed accurate vision. (shrink)

What is the relationship between observations, predictions, texts, and instruments in ancient astrology? By distinguishing between two distinct kinds of observation claim in astrological texts, I show on the one hand the rhetorical and theoretical importance of each kind of observation claim to ancient astrological traditions, and on the other hand how practices of ancient astrology break from observation once astronomical phenomena become reliably predictable. We thus see a shift in practice from observationally derived predictions to a (...) reliance on textual and instrumental authority, even though the rhetoric of ancient astrology still tries to maintain an emphasis on observation.Author Keywords: Astrology; Astrometeorology; Astronomy; Divination; Instruments; Observation; Parapegmata; Prediction; Rhetoric; Signs; Weather. (shrink)

Some variants in the materials related to the planetary latitudes, including computational procedures, underlying parameters, numerical tables, and so on, may be addressed in the corpus of the astronomical tables preserved from the medieval Islamic period, which have already been classified comprehensively by Van Dalen. Of these, the new values obtained for the planetary inclinations and the longitude of their ascending nodes might have something to do with actual observations in the period in question, which are the main concern of (...) this paper. The paper is in the following sections. In the first section, Ptolemy’s latitude models and their reception in Islamic astronomy are briefly reviewed. In the next section, the medieval non-Ptolemaic values for the inclinations and the longitudes of the nodal lines are introduced. The paper ends with the discussion and some concluding remarks. The derivation of the underlying inclination values from the medieval planetary latitude tables and determining the accuracy of the tables are postponed to “Appendix” in the end of the paper. (shrink)

ABSTRACTThe known works of the medieval astronomer/astrologer Henry Bate include a set of planetary mean motion tables for the meridian of his Flemish hometown Mechelen. These tables survive in three manuscripts representing two significantly different recensions, but have never been examined for their principles of construction or underlying parameters. Such analysis reveals that Bate employed an unusual value for the length of the tropical year, which was probably derived by comparing ancient and contemporary observations of the vernal equinox. In addition, (...) there are clear signs that Bate kept revising his parameters for the mean motions of Venus and the three superior planets, none of which can be traced back to earlier sources. Together with some of Bate’s preserved statements, these findings support the conclusion that the Tabule Machlinenses were unique among the astronomical tables produced in medieval Latin Christendom for using independently derived parameters that were the result of new observations. Bate’s achievement connects him to a wider milieu of astronomers operating in late-thirteenth-century Paris, who put an increased emphasis on observation and the critical examination of received data. (shrink)

In this paper, we analyze the astronomical tables in al-Zīj al-Muqtabis by Ibn al-Kammād (early twelfth century, Córdoba), based on the Latin and Hebrew versions of the lost Arabic original, each of which is extant in a unique manuscript. We present excerpts of many tables and pay careful attention to their structure and underlying parameters. The main focus, however, is on the impact al-Muqtabis had on the astronomy that developed in the Iberian Peninsula and the Maghrib and, more generally, on (...) the transmission and diffusion of Indian astronomy in the West after the arrival of al-Khwārizmī’s astronomical tables in al-Andalus (Muslim Spain) in the tenth century. This tradition of Indian origin competed with the Greek tradition represented by al-Battānī’s astronomical tables and was much more alive in the Iberian Peninsula and the Maghrib than previously thought. From Spain, the Indian tradition entered mainstream European astronomy, where we find echoes of it in all versions of the Alfonsine Tables, both in manuscript and in the printed editions (beginning in 1483), as well as in Copernicus’s De Revolutionibus, published in 1543. (shrink)

A country‘s development is bound to be influenced by external occurrences. This article analyses two astronomical examples in which Portuguese nationals used high visibility events in the international scientific community to press their own scientific interests upon the government, whether these interests were, or were not, directly linked to the events themselves.During the 1840s and 1850s the parallax, i.e. the distance, of Groombridge’s star 1830 was hotly debated. The astronomer Hervé Faye‘s suggestion at the Académie des Sciences de Paris that (...) observations be made in Lisbon due to its privileged location and the inadequacy of the Lisbon Navy Observatory to perform them rekindled the efforts to improve the Portuguese Navy observatory.In the 1850s and 1860s other Portuguese higher education institutions also wanted to upgrade their facilities or build new ones. Following accepted traditions, scientific field trips were considered a useful part of the acquisition planning for larger instruments, and therefore an important part of regeneration and renewal projects. The Portuguese scientists were, however, limited in their travels by government imposed budget constraints. The total solar eclipse of 18 July 1860 provided an extra argument to send Portuguese scientists abroad. The government support of the eclipse expedition led to an opportunity to travel through other countries and view their observatories and equipment.In the end, neither the Navy astronomers nor those from the Coimbra Astronomical observatory, the other significant site of Portuguese astronomical research, managed to fulfil their objectives, but the contacts initiated by some of the Portuguese travellers were important for the development of the Portuguese national Meteorological and Magnetic Observatories. (shrink)

In the framework of contemporary cosmology, the age-old aspiration to inquire the outer limits of the universe translates into our effort to observe the initial stages of cosmic history. Thanks to a fortunate combination of astronomical circumstances, and pushing mm-wave technology to its limits, today we are able to image the early universe in great detail, back at a time when cosmic age was only 0.0027% of its present value. The state of the art in the field has been set (...) by the ESA Planck mission, launched in 2009, dedicated to precision measurements of the cosmic microwave background. Planck observed the full sky for 4 years in a wide frequency range, reaching μK sensitivity both in temperature and polarization. The latest results, published by the Planck Collaboration in 2018, are in exquisite agreement with the simplest 6-parameter ΛCDM model and constrain the main cosmological parameters with percent-level accuracy. Furthermore, the Planck data yield insight on the very early universe, opening the way to a new generation of experiments searching for the possible signatures of primordial gravitational waves in the CMB polarization pattern. (shrink)

The manuscripts and writings of the fifteenth-century astronomer and physician Lewis Caerleon (d. c. 1495) have been largely overlooked. To fill this gap, this article focuses on his writings and working methods through a case study of his canons and table for the equation of time. In the first part, an account of his life and writings is given on the basis of new evidence. The context in which his work on the equation of time was produced is explored in (...) detail by reviewing the three key periods of his scientific production. His heavy reliance on Simon Bredon’s Commentum super Almagesti is also analyzed. The article also provides editions of Lewis Caerleon’s canons for calculating his table for the equation of time and a critical edition of Simon Bredon’s Commentum super Almagesti, III, 22–24. In the second part of this article, we analyze the table for the equation of time derived by Lewis around 1485. In addition to the final table, there is a unique table with intermediate results that records every step of his derivation. By following and discussing the details of this derivation, we shed a new light on tabular practices in mathematical astronomy. Following Lewis in his historical mathematical procedure, we argue, offers a novel historiographical approach that allows us to identify different sources and practices used by historical actors. Therefore, beyond the exchange of parameters residing in modern mathematical analysis, this novel approach offers a promising refinement for the analysis of the transmission of knowledge across space, time, and culture. (shrink)

According to the received view, the first spyglass was assembled without any theory of how the instrument magnifies. Galileo, who was the first to use the device as a scientific instrument, improved the power of magnification up to 30 times. How did he accomplish this feat? Galileo does not tell us what he did. We hold that such improvement of magnification is too intricate a problem to be solved by trial and error, accidentally stumbling upon a complex procedure. We construct (...) a plausibility argument and submit that Galileo had a theory of the telescope. He could develop it by analogical reasoning based on the phenomenon of reflection in mirrors—as it was put to use in surveying instruments—and applied to refraction in sets of lenses. Galileo could appeal to this analogy and assume Della Porta’s theory of refraction. He could thus turn the spyglass into a revolutionary scientific instrument—the telescope. (shrink)

In astronomy Abraham Zacut is best known for the Latin version of his tables, the Almanach Perpetuum, first published in 1496, based on the original Hebrew version that he composed in 1478. These tables for Salamanca, Spain, were analyzed by the authors of this paper in 2000. We now present Zacut’s tables preserved in Latin and Hebrew manuscripts that have not been studied previously, with a concordance of his tables in different sources. Based on a hitherto unnoticed text in a (...) Latin manuscript, we argue that Zacut is the author of the Tabule verificate which, in our publication of 2000, we took to be anonymous. We also discuss in detail Zacut’s tables for epoch 1513 for Jerusalem that are arranged for the Hebrew calendar, rather than the Julian calendar that he used elsewhere. We then consider a number of fragmentary texts that were found in the Cairo Geniza, now scattered in various European and American libraries. The new evidence is consistent with our earlier finding that Zacut depended both on the medieval Hebrew tradition in astronomy and on the Parisian Alfonsine Tables. (shrink)

An outdated geography supplies the bond among the thirty‐one articles in Sur les traces des Cassini. In the seventeenth century, when the Italians Gian Domenico Cassini and his nephew Giacomo Filippo Maraldi were born in Perinaldo, north of Genoa, their birthplace belonged to the County of Nice. Hence the rationale of building a set of papers on astronomy in the south of France around Cassini I and his family, which for four generations ran the Royal Observatory in Paris.Over half the (...) articles concern the Cassinis, mostly Cassini I and his great‐great‐grandson and namesake Cassini IV. There was also a Cassini V, Henri de Cassini, who countered the family genius and stamina by preferring botany and dying early, of the same outbreak of cholera that took the life of Sadi Carnot, without having created Cassini VI. He had already entered the Academy of Sciences with a push from his father. “I dare to beg of you [Cassini IV wrote to his fellow academician A. M. Ampère] to consider whether this unique situation in the history of letters, [a family's] devotion to the sciences for five successive generations and 170 years, ought not add some weight to the scientific credentials of my son.” It is hard to refuse the children of important alumni.The portion of Traces dealing more directly with astronomy in the south of France gets off to a distant start. Pytheas of Marseilles, who lived about 350 b.c., sailed to the Orkneys and the Baltic and earned himself the reputation of a liar back home for his stories of midnight suns and frozen lakes. He measured the latitude of Marseilles, the obliquity of the ecliptic, and the size of the earth. Ptolemy praised him. Strabo did not: “Pytheas lied about everything and covered it up with his knowledge of astronomy and numbers.”No traces worth following up were laid down for just under two thousand years. Then, in 1580, Nicolas Fabri de Peiresc first saw the light of day. He lived in Italy for four years as a very young man, deepening his knowledge of astronomy and human nature and meeting the main future actors in the Galileo affair: Galileo himself, Bellarmine, and Matteo Barberini . At his center in Aix‐la‐Provence, Peiresc made many useful astronomical observations, some in collaboration with Pierre Gassendi. He died in harness, worrying about the change of the obliquity since the days of Pytheas.There follow articles on Provençal astronomers who determined longitude and latitude at sea, on neglected observers in Languedoc who assisted the cause of the Enlightenment, and on modern observatories in the south of France. The political circumstances after the defeat of 1870–1871 favored decentralization of astronomy away from the Paris Observatory. In Italy, too, recent political events—the unification of 1870—made a restructuring of astronomical institutions desirable and possible. But whereas France had too few observatories, Italy had too many. Georges Rayet and Pietro Tacchini, both astrophysicists, compared the circumstances in their countries and made mutually reinforcing proposals to their colleagues and governments. Their respective proposals, most of which were enacted, called for reassigning some Italian observatories to meteorological work, building new observatories in Besançon, Bordeaux, and Lyon, and refurbishing older ones at Marseilles and Toulouse. Once again, as in the days of Cassini I, Italy made a decisive contribution to the practice of astronomy in France.Sur les traces des Cassini mixes slight and weighty work, admits antiquarian and broader approaches, offers new documentation, displays pertinent illustrations, and does it all at a high level of scholarship. Since, because of its title, the book's primary audience probably will be people interested in the Cassinis, its fullest articles about them may usefully be mentioned here: Anna Cassini on Cassini's brief return to Italy, 1694–1696; Claude Teillet on the provincial life and poetry of Cassini IV; Christiane Demeulenaere‐Douyère on the Cassinis and the Académie des Sciences; Fabrizio Bonoli and Alessandro Braccesi on Cassini I's astronomical work in Bologna, with full bibliography; and Monique Pelletier on the Cassini map of France, on which she has written a book . Pytheas and Peiresc are the subjects of collaborative articles by Simone Arzano and Yvon Georgelin. (shrink)

Britain's nineteenth-century railway companies traditionally play a central role in histories of the spread of standard Greenwich time. This relationship at once seems to embody a productive relationship between science and capitalism, with regulated time essential to the formation of a disciplined industrial economy. In this narrative, it is not the state, but capitalistic private commerce which fashioned a national time system. However, as this article demonstrates, the collaboration between railway companies and the Royal Greenwich Observatory was far from harmonious. (...) While railways did employ the accurate time the observatory provided, they were also more than happy to compromise the astronomical institution's ability to take the accurate celestial observations that such time depended on. Observing astronomical transits required the use of troughs of mercury to reflect images of stars, but the construction of a railway too near to the observatory threatened to cause vibrations which would make such readings impossible. Through debates over proposed railway lines near the observatory, it becomes clear how important government protection from private interests was to preserving astronomical standards. This article revises our understanding of the role of railway companies in the dissemination of standard time and argues that state intervention was essential to preserving Victorian British astronomical science. (shrink)

HISTORY HAS IT that the four bright satellites of Jupiter were discovered independently by Galileo and the German astronomer Simon Mayer in the early seventeenth century. These initial glimpses of what we now call the Galilean moons of Jupiter are among the first great revelations to have accrued from pointing the newly invented telescope toward the heavens. Yet, were these men the first to observe Jupiter’s satellites? There have been persistent reports, particularly in the nineteenth century, that these moons can (...) be seen with the naked eye. (shrink)

Summary The Almagest of Ptolemy (mid-second century ad) contains eleven dated reports of observations of the positions of planets made during the third century bc in Babylon and Hellenistic Egypt. The present paper investigates the character, purpose, and conventions of the observational programmes from which these reports derive, the channels of their transmission to Ptolemy's time, and the fidelity of Ptolemy's presentation of them. Like the Babylonian observational programme, about which we have considerable knowledge through cuneiform documents, the Greco-Egyptian ones (...) were not directed towards the deduction of mathematical models of celestial motion but appear to have investigated patterns, correlations, and periodicities of phenomena. Ptolemy's immediate sources most likely were not the original series of observational records, but treatises by various astronomers of the intervening four centuries, including Hipparchus. While Ptolemy does not appear to have tampered with the wording of the reports, he faced difficulties and uncertainties in interpreting them; critically, he lacked sufficiently detailed information about the ancient calendars to be able to convert the reported dates accurately into his own chronological framework based on the Egyptian calendar. (shrink)