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Article

John Steele

The term “Babylonian astronomy” is used to refer to a diverse range of practices undertaken by people in ancient Babylonia and Assyria including what in modern English would be referred to as astronomy, astrology and celestial divination, and cosmology. The earliest astronomical or astrological texts preserved from Babylonia and Assyria date to the early 2nd millennium bce, although some basic astronomical knowledge such as the identification of a regular cycle of the moon, the identification of the planets as a distinct type of celestial object from the stars, and the grouping of stars into constellations dates back much earlier, perhaps even before the development of writing in the 4th millennium bce. Astronomical and astrological texts were still being written around 2,000 years later during the 1st century ce. These texts are some of the latest known texts written in cuneiform. Babylonian astronomy encompassed a range of practices, including the cataloguing of stars and constellations, the regular observation of celestial phenomena, the development and use of methods of predicting those same phenomena, and the interpretation of observed and computed astronomical data through various forms of astrology.

Article

Alexander Jones

During the Hellenistic and Roman periods, tables were extensively employed in Graeco-Roman astronomy to present structured, quantitative astronomical data for reference, calculation, and display of patterns of data. Media for tables included papyrus, in roll or codex format, wooden boards, and occasionally inscriptions. Aside from their didactic function in writings on theoretical astronomy such as Ptolemy’s Almagest, the chief practical applications of astronomical tables were in astrology. Tables for calculating celestial positions and phenomena of the heavenly bodies represented two distinct traditions: an originally Babylonian tradition based on arithmetical operations and a Greek tradition, best known from Ptolemy’s works, based on trigonometry relating to geometrical theories for the motions of the Sun, Moon, and planets. Both traditions made use of sexagesimal place-value notation. Additionally, almanacs and calendrically structured ephemerides presented celestial positions calculated over long spans of dates as a convenient tool for horoscopy and the astrological evaluation of days.

Article

The subject of astronomy in folk tradition, or folk astronomy, requires some explication. It is, for instance, not the same as ethnoastronomy, which primarily studies the astronomical ideas of contemporary societies. However, the subject overlaps with archaeoastronomy when defined widely as the interdisciplinary study of prehistoric, ancient, and traditional astronomies worldwide within their cultural context that includes both written and archaeological records. The most useful definition of “astronomy in folk tradition” might be “astronomy of the people or of the common man,” or even “lay astronomy,” left to us through tradition, where the term “astronomy” may, for further clarity, be replaced by “ideas and observations of the sky.” In any case, it is worth keeping in mind that the content of folk astronomy of one society may overlap with the content of established astronomy of another society at another time and place. Scientific ideas or theories have their roots in the past, even before the advent of any “experts.” Folk astronomy of the past is often less accessible for historical studies than mainstream astronomy, especially in a society leaving few records or artifacts. Revealing sources may, however, be found by looking beyond the conventional. For instance, various sources on mythology and religion may give information on the astronomical and cosmological ideas of previous societies. Purportedly fictional literature, like the works of Dante and Chaucer, may also yield information of this kind, although they were not explicitly composed for that purpose. But there are also writers who have deliberately written on the astronomical ideas of their society at their time, although their works were outside of the best known corpus and sometimes intended for common people. Two Old Norse examples are the 13th-century Norwegian King’s Mirror and the Icelandic 12th- to 14th-century material edited in the volume of Alfræði íslenzk II. Among other things, these sources treat phenomena that are not observable outside the subarctic region. A third example is the 14th–15th century North European Seebuch with practical information for seamen, partly linked to astronomy. In any case, two types of folk astronomy can be distinguished: (a) practical astronomy that people use as a tool in daily life, for example, to determine the time of day or year, or for travel and navigation; (b) ideas related to cosmology or cosmogony, religion, or supernatural beliefs, which would neither imply practical uses nor consequences.

Article

In the Middle Ages and Renaissance, alchemy and astrology shared a common language in the meanings and characters attributed to the celestial bodies, which provided a cosmic framework for understanding all terrestrial affairs. Astrology is the name given to a series of diverse practices based in the idea that the stars, planets, and other celestial phenomena possess significance and meaning for events on the Earth. In practical terms, astrology’s function was to predict the future, manage the present, and understand the past. In the Middle Ages and Renaissance, these three functions were not seen as separate, because time existed as a single entity—past, present, and future coexisted in the mind of God. Astrology assumed a link between Earth and sky in which all existence, spiritual, psychological, and physical, is interconnected. Time and space existed in a mutually dependent continuum, in which both were infused with the same qualities, represented in terms of astrological language by zodiac signs and planets. The practice of alchemy applied such assumptions to the material world, attempting to convert one metal into another, typically lead into gold. As all things were interconnected, including soul and body, the physical practice of alchemy was intimately connected with spiritual practice intended to purify the soul in preparation for its meeting with the divine. The planets had roles in both astrology and alchemy. A planet, from the Greek planētai, meaning wanderer, is a star, a point, or source of light in the sky that constantly alters its position. This is in contrast to the so-called fixed stars, which appear to keep exactly the same position relative to each other, at least over historic periods of time. Technical astrology largely developed in the Hellenistic, Greek-speaking world from the early third century BCE onward. With the collapse of the Roman Empire and classical learning in most of Western Europe from the 5th century, the complex astrology of the Classical world largely disappeared. It returned to Western Europe in two phases. The first phase, mainly in the 12th century, included the translation into Latin of major texts from Arabic, including those originally composed in Greek, and was accompanied by Aristotelian works that justified the use of astrology in naturalistic terms, thereby negating Christian disapproval. Alchemy was introduced into Western Europe at the same time. The second phase began mainly in the 15th century, during the Renaissance, as part of a wider revival of Classical thought encouraged by the translation of Platonic, neo-Platonic, and Hermetic works from Greek directly into Latin. By the end of the 17th century, the practice of both astrology and alchemy had largely disappeared. Astrology was confined to popular almanacs and alchemy was replaced by modern chemistry.

Article

Astrology was a central feature of Greek and Roman culture. A knowledge of astrology’s claims, practices, and world view is essential for a full understanding of religion, politics, and science in the Greek and Roman worlds. Astrology is the name given to a series of diverse practices based in the idea that the stars, planets, and other celestial phenomena possess significance and meaning for events on Earth. It assumes a link between Earth and sky in which all existence, spiritual, psychological, and physical, is interconnected. Most premodern cultures practice a form of astrology. A particularly complex variety of it evolved in Mesopotamia in the first and second millennia bce from where it was imported into the Hellenistic world from the early 4th century bce onward. There it became attached to three philosophical schools, those pioneered by Plato, Aristotle and the Stoics, all of which shared the assumption that the cosmos is a single, living, integrated whole. Hellenistic astrology also drew on Egyptian temple culture, especially the belief that the soul could ascend to the stars. By the 1st century ce, the belief in the close link between humanity and the stars had become democratized and diversified into a series of practices and schools of thought which ranged across Greek and Roman culture. It was practiced at the imperial court and in the street. It could be used to predict individual destiny, avert undesirable events, and arrange auspicious moments to launch new enterprises. It could advise on financial fortunes or the condition of one’s soul. It was conceived of as natural science and justified by physical influences or considered to be divination, concerned with communication with the gods and goddesses. In some versions, the planets were neither influences nor causes of events on Earth, but timing devices, which indicated the ebb and flow of human affairs, like the hands on a modern clock. Astrology had a radical view of time in which the future already existed, at least in potential, and the astrologer’s task was to intercede in time, altering the future to human advantage. In this sense astrology was a form of “participation mystique” in which time and space were conceived of as a single entity and individual and social benefits were to be derived from engaging with it. There was no one single version of astrology and there were disputes about what it was and what it could do, for example, whether it could make precise predictions about individual affairs or merely general statements. From the early 4th century it went into a progressive decline, facing challenges from Christianity and the fragmentation of classical culture, especially in Western Europe. It survived in Persia, exerted a powerful influence on Indian astrology, and was transmitted to the Islamic world, from where it was reimported into the Latin West in the 12th century.

Article

Duane W. Hamacher and Kirsten Banks

Studies in Australian Indigenous astronomical knowledge reveal few accounts of the visible planets in the sky. However, what information we do have tells us that Aboriginal people are close observers of planets and their motions and properties. Indigenous Australians discerned between planets and stars by their placement in the sky and their general lack of scintillation. Traditions generally describe the ecliptic and zodiac as a pathway of sky ancestors represented by the sun, moon, and planets. This included observing the occasional backwards motion of sky ancestors as they communicate with each other during their journey across the sky, representing an explanation of retrograde motion. Aboriginal and Torres Strait Islander people note the relative brightness of the planets over time and information about the roles they play in their traditions around Australia. Knowledge systems outline the importance placed on Venus as the morning and evening star, making connections to the object as it transitions form one to the other through observations and calculation of the planet’s synodic period. Traditions note the relative positions of the planets to the moon, sun, and background stars, as well as inter planetary dust through zodiacal light, which is perceived as a celestial rope connecting Venus to the sun. The relative dearth of descriptions of planets in Aboriginal traditions may be due to the gross incompleteness of recorded astronomical traditions and of ethnographic bias and misidentification in the anthropological record. Ethnographic fieldwork with Aboriginal and Torres Strait Islander communities is revealing new, previously unrecorded knowledge about the planets and their related phenomena.

Article

Daryn Lehoux

Greek and Roman astrology was a culturally significant system of understanding the cosmos and people’s place in it. Astrology believed (and indeed, argued) that human destinies could be predicted, explained, or understood by looking at the positions of the planets and the orientation of the zodiac relative to the moment of an individual’s birth. Astrology was widely practiced and consumed at all levels of Greco-Roman society from approximately the first century bce onward. Details of how the system worked could vary from author to author, sometimes reaching impressive levels of computational or interpretative complexity. Astrology is one of the more prominent cultural exports of classical antiquity, still widely consumed, often in the form of (much simplified) daily horoscopes in newspapers or online.Astrology is the practice of converting astronomical data (including the positions and relationships of celestial bodies) into predictions or explanations of terrestrial events. Classical astrology developed in the Hellenistic age, as a modification of earlier Babylonian practices. .

Article

Hypatia  

Henriette Harich-Schwarzbauer

The philosopher Hypatia (350/370–415 ce) is one of the outstanding figures in the intellectual life of Late Antiquity. She is considered a symbol of the transformation of science and philosophy under the Christian bishops in Alexandria at the end of the 4th century ce. Her life and her works are well documented in different literary genres and by famous authors, namely by Synesius of Cyrene in his letters. The extant testimonies on her work prove that she was the guiding light of astronomy in Alexandria, where she was held in high esteem. Unsurprisingly, she became the target of aggression, and she was murdered ferociously in 415. Hypatia has been commemorated in the Byzantine and the Western traditions. She has experienced an impressive revival since the Enlightenment; even in the 21st century she is depicted as a heroine in fiction and film.Hypatia appears to have spent her entire life in her hometown of .

Article

Alexander Jones

The Antikythera Mechanism (National Archaeological Museum, Athens, inv. X 15087) was a Hellenistic gearwork device for displaying astronomical and chronological functions. Substantial but highly corroded remains of the instrument were recovered from an ancient shipwreck (see Figure 1).

The most complex scientific instrument to have survived from antiquity, it resembled the sphaerae or planetaria described by Cicero (1) and other Greco-Roman authors. The date of its construction is in dispute but must have been earlier than the middle of the 1st centurybce and can scarcely have been before the end of the 3rd centurybce. It is an invaluable witness for ancient mechanical technology at its most advanced level (see mechanics) as well as for Hellenistic astronomy.

Article

Historical emergences of new communications technologies have had a dramatic impact on the structures of international contact. While these advances come in many forms, they all affect the ecology of international communications. Some forms of advances, such as the physical, are often overlooked and perhaps even trivialized. Advances like the stirrup and hay allowed increased movements, often in the form of conquests that brought disparate people and cultures into physical contact. Intellectual advancements such as the scientific method, mathematics like calculus and trigonometry, Copernicus’s heliocentrism, and Darwin’s theory of evolution bridged international boundaries through the formation and maintenance of international academic communities.

Article

Anthropologists distinguish the U.S. State of California as a primary zone of prehistoric and tribal North America—it was one of the most linguistically and cultural diverse regions on earth. The original population of Native California and traditional cultures were decimated by the Spanish, the Mexicans, and the Anglos, who successively settled California and transformed it. For that reason, knowledge of the character and function of astronomy in what is now California prior to European contact in the 16th century is incomplete and fragmented. Traditional astronomical lore is preserved in a few ethnohistoric commentaries, in some archaeological remains, and in ethnographic research conducted primarily in the early 20th century, when elements of indigenous knowledge still survived. Throughout Native California, the moon’s conspicuous brightness, movement, and systematically changing appearance prompted its affiliation with seasonal change, the passage of time, and cyclical renewal, and most California tribes monitored and counted lunations in one way or another, but not necessarily throughout the entire year. In some cases, individual lunations were affiliated with and named for seasonal circumstances. There is little evidence, however, for even minimal interest in or recognition of the planets visible to the unaided eye, with the exception of Venus as the “Morning Star” or “Evening Star.” Venus, like the moon and other celestial objects, was personified and regarded as a fundamental and active agent of the cosmos. There is no evidence, however, for detailed monitoring of Venus and quantitative knowledge of its synodic behavior.

Article

Although the Inca state (ca. 1200–1572 ce) was called the Empire of the Sun, the Moon was, in some respects, an equally important divinity in the official state cult. The regulatory function of the phases of the synodic cycle of the Moon in different kinds of social activities, especially those framed in calendrical systems but also military campaigns, is well documented. As far as the orientation of architectural structures is concerned, the researchers focus their attention almost entirely on the position of the Sun. However, a more accurate analysis of two well-known sites—the caves of Intimachay and Inkaraqay—may provide evidence of their function as observatories of the lunar 18.6-year cycle. Those results may confirm the hypothesis, presented some years ago, that the Incas had elaborated a rudimentary method of predicting lunar eclipses. The determination of the exact role of Venus and other planets in the Inca worldview encounters a serious limitation: in contrast to Mesoamerica, in Tahuantinsuyu and the Andes, there are no important “first-hand” sources such as the calendrical-astronomical data of the Maya or the Aztecs. Only Venus seems to have enjoyed a cult of Pan-American range. The morning appearance of Venus was apparently related to the puberty initiation rites of male adolescents, while its appearance as Evening Star seems to have been closely symbolically related to the Inca sovereign and his military activities. Putting aside the information available on Venus and its cult, there is an almost complete lack of data on the other planets. Another problem must be considered: To what extent did the Incas inherit their knowledge from their predecessors, the Chimus, or even earlier cultures?

Article

In ancient Mesopotamia, all five planets visible to the naked eye were known and studied, along with the Moon, the Sun, the stars, and other celestial phenomena. In all Mesopotamian sources concerning the Moon and the planets, be they textual or iconographical, the astronomical, astrological, and religious aspects are intertwined. The term “astral science” covers all forms of Mesopotamian scholarly engagement with celestial entities, including celestial divination and astrology. Modern research on Mesopotamian astral science began in the 19th century. Much research remains to be done, because important sources remain unpublished and new questions have been posed to published sources. From ca. 3000 bce onward, Mesopotamians used a calendar with months and years, which indicates that the Moon was studied at that early age. In cuneiform writing, the Sumerian and Akkadian names of the Moongod, Nanna/Sin, are attested since ca. 2500 bce. The most common Akkadian names of the five planets, Šiḫṭu (Mercury), Dilbat (Venus), Ṣalbatānu (Mars), White Star (Jupiter), and Kayyāmānu (Saturn), are attested first in 1800–1000 bce. The Moon, the Sun, and the planets were viewed as gods or manifestations of gods. From ca. 1800 bce onward, the phenomena of the Moon, the Sun, and the planets were studied as signs that were produced by the gods to communicate with humankind. Between ca. 600 bce and 100 ce, Babylonian scholars reported lunar and planetary phenomena in astronomical diaries and related texts. Their purpose was to enable predictions of the reported phenomena with period-based, so-called Goal-Year methods. After the end of the 5th century bce Babylonian astronomers introduced the zodiac and developed new methods for predicting lunar and planetary phenomena known as mathematical astronomy At about the same time they developed horoscopy and other forms of astrology that use the zodiac, the Moon, the Sun, and the planets to predict events on Earth.

Article

John MacDonald

Inuit are an indigenous people traditionally inhabiting the Arctic and sub-Arctic regions of Greenland, Canada, Alaska, and parts of Russia’s Chukchi Peninsula. Across this vast region, Inuit society, while not entirely homogeneous either culturally or linguistically, nevertheless shares a fundamental cosmology, in part based on a common understanding of the sky and its contents. Traditionally, Inuit used prominent celestial objects—the sun, moon, and major circumpolar asterisms—as markers for estimating the passage of time, as wayfinding and directional aids, and, importantly, as the basis of several of the foundational myths and legends underpinning their society’s social order and mores. Random inquiries on Inuit astronomy made by European visitors after initial contact through the mid-18th and early 20th centuries were characteristically haphazard and usually peripheral to some other line of ethnological enquiry, such as folklore or mythology. In addition, the early accounts of Inuit star lore were often prone to misrepresentation due to several factors, including European cultural bias, translation inadequacies, a deficiency of general astronomical knowledge on the part of most commentators, and, most significantly, a failure—sometimes due to lack of opportunity—to conduct systematic observations of the sky in the presence of Inuit knowledge holders. Early accounts therefore tended to diminish the cultural significance of Inuit astronomy, almost to the point of insignificance. Unfortunately, by the time systematic fieldwork began on the topic, in the mid-1980s, unalloyed information on Inuit astronomical knowledge was already elusive, more and more compromised by European acculturation and substitution and, notably, by light pollution—a consequence of the increasing urbanization of Inuit communities beginning in the late 1950s. For the residents of most Arctic settlements, street lights reflecting off the snow have virtually eliminated the evocative phenomenon of the “polar night.” For several reasons, the role of planets in Inuit astronomy is difficult to determine, due, in part, to the characteristics of the planets themselves. Naked-eye differentiation between the major visible planets is by no means straightforward, and for observers living north of the Arctic Circle, the continuous or semicontinuous periods of daylight/twilight obtaining throughout the late spring, summer, and early fall effectively prevent year-round viewing of the night sky, making much planetary movement unobservable, far less an appreciation of the planets’ predictable synodic and sidereal periods. Mitigating against the significant use of planets in Inuit culture is also the principle that their applied astronomy, along with its cosmology and mythologies depend principally on—apart from the sun and the moon—the predictability of the “fixed stars.” Inuit of course did see the major planets and took note of them when they moved through their familiar asterisms or appeared, irregularly, as markers of solstice, or harbingers of daylight after winter’s dark. Generally, however, planets seem to have been little regarded until after the introduction of Christianity, when, in parts of the Canadian eastern Arctic, Venus, in particular, became associated with Christmas. While there are anecdotal accounts that some of the planets, again especially Venus, may have had a place in Greenlandic mythology, this assertion is far from certain. Furthermore, reports from Alaska and Greenland suggesting that the appearance of Venus was a regular marker of the new year, or a predictor of sun’s return, need qualification, given the apparent irregularity of Venus’s appearances above the horizon. A survey of relevant literature, including oral history, pertaining either directly or peripherally to Inuit astronomical traditions, reveals few bona fide mention of planets. References to planets in Inuit mythology and astronomy are usually speculative, typically lacking supportive or corroborative information. It can therefore be reasonably inferred that, with the qualified exception of Venus, planets played little part in Inuit astronomy and cosmology despite their being, on occasion, the brightest objects in the Northern celestial sphere. This being the case, there is a certain irony in NASA’s recently bestowing Inuit mythological names on a group of Saturn’s moons—Saturn being a planet the Inuit themselves, as far as can be determined, did not note or recognize.

Article

By 2020, it is expected that approximately 70 % of the world’s surface astronomical observation will be located in Chile, considering both optical and infrared telescopes, belonging to international institutions. How did this happen? Can we explain the overwhelming importance of astronomy in this southern country only because of its geography? This process began when scientists from Europe, the United States, and the Soviet Union went to Chile in the 1960s, and each one of them decided to build a massive observatory in the country. The atmospheric conditions certainly had a role in these decisions, but they were also related to Cold War politics and, indirectly, to the previous history of astronomy in Chile. The international dimension of astronomy in Chile had been preset since the mid-19th century, when the first modern astronomy initiative took place. An American expedition built the first observatory, which later became the National Astronomical Observatory. By the early 20th century, another American expedition had arrived in Chile, and this one stayed for more than twenty years. Decades later, the global dimension of astronomy took the decisive step in the southern country and set the milestone for the development in the hands of Europeans, Americans and Soviets. In the process, Chileans became involved with astronomy, trying to promote science, the country’s international relations, and to grasp the attractions of modernity.

Article

During the 518 years of Korea’s Chosŏn dynasty (1392–1910), many things changed and many things stayed the same. After the Yi family established the Chosŏn dynasty, Confucianism became the dominant philosophy. Although Confucianism’s grip on Chosŏn weakened somewhat at the end of the 19th century, it nevertheless continued to provide the basic framework for how government officials and most of the educated elite conceptualized ethics, religion, nature, and technology. This changed when the Chosŏn dynasty was absorbed into the Japanese empire in 1910. Chosŏn-era science, technology, and religion operated within a Confucian framework. This affected astronomical, geographical, mathematical, and medicinal thought and practice. It also affected the role of technology in Chosŏn life and society. Moreover, when Buddhism, folk religion and, from the end of the 18th century even Christianity, were practiced in Korea, it was necessary to maneuver within constraints imposed by a Confucian state and society. Korea’s Confucianism was imported from China. Koreans, however “Koreanized” what they adopted from China to make it their own. When dealing with religion, Chosŏn-era Koreans adopted a much harsher attitude toward non-Confucian religions. When dealing with science and technology, Koreans sometimes made improvements on Chinese models. For example, in the 15th century, Koreans built astronomical instruments that were better than those they had learned about from Chinese astronomers. And, in the 17th century, Koreans produced the most comprehensive encyclopedia of traditional East Asian medicine of pre-modern times. However, none of those changes threatened the hegemony of Confucianism. Chosŏn Korea remained Confucian in its science, technology, and religiosity for over five centuries.

Article

James D. Burke and Erik M. Conway

The Jet Propulsion Laboratory (JPL) of the California Institute of Technology had its origins in a student project to develop rocket propulsion in the late 1930s. It attracted funding from the U.S. Army just prior to U.S. entry into World War II and became an Army missile research facility in 1943. Because of its origins as a contractor-operated Army research facility, JPL is the National Aeronautics and Space Administration’s (NASA) only contractor-operated field center. It remains a unit of the California Institute of Technology. In the decades since its founding, the laboratory, first under U.S. Army direction and then as a NASA field center, has grown and evolved into an internationally recognized institution generally seen as a leader in solar system exploration but whose portfolio includes substantial Earth remote sensing. JPL’s history includes episodes where the course of the laboratory’s development took turning points into new directions. After developing short-range ballistic missiles for the Army, the laboratory embarked on a new career in lunar and planetary exploration through the early 1970s and abandoned its original purpose as a propulsion technology laboratory. It developed the telecommunications infrastructure for planetary exploration too. It diversified into Earth science and astrophysics in the late 1970s and, due to a downturn in funding for planetary exploration, returned to significant amounts of defense work in the 1980s. The end of the Cold War between 1989 and 1991 resulted in a declining NASA budget, but support for planetary exploration actually improved within NASA management—as long as that exploration could be done more cheaply. This resulted in what is known as the “Faster Better Cheaper” period in NASA history. For JPL, this ended in 2000, succeeded by a return to more rigorous technical standards and increased costs.

Article

While the moon naturally featured in Mediterranean cultures from time immemorial, principally noted in the earliest literature as a marker of time, time-dependent constructs such as the calendar, and time-related activities, awareness and recognition of the five visible planets came relatively late to the Greeks and thence to the Romans. The moon underlies the local calendars of the Greeks, with documentary and literary evidence from the Late Bronze Age through the Imperial Roman period, and there are signs that the earliest Roman calendar also paid homage to the moon in its divisions of the month. However, although Homer in the 8th century BCE knows of a Morning and an Evening Star, he shows no indication of realizing that these are one and the same, the planet Venus. That particular identification may have come in the 6th century BCE, and it appears to have been not until the 4th century BCE that the Greeks recognized the other four planets visible to the naked eye—Saturn, Jupiter, Mars, and Mercury. This awareness probably came via contact with Babylonian astronomy and astrology, where identification and observations of the planets had figured from the 2nd millennium BCE and served as a basis for astrological prognostications. But it is time, not astrology, that lies at the heart of Greek and Roman concerns with the moon and the planets. Indeed, the need to tell time accurately has been regarded as the fundamental motivation of Greek astronomy. A major cultural issue that long engaged the Greeks was how to synchronize the incommensurate cycles of the moon and the sun for calendrical purposes. Given the apparent irregularities of their cycles, the planets might seem to offer no obvious help with regard to time measurement. Nonetheless they were included by Plato in the 4th century BCE in his cosmology, along with the sun and moon, as heavenly bodies created specifically to compute time. Astrology then provided a useful framework in which the sun, moon, planets, and stars all combined to enable the interpretation and forecasting of life events. It became necessary for the Greeks, and their successors the Romans, to be able to calculate as accurately as possible the positions of the heavenly bodies in order to determine readings of the past, present, and future. Greek astronomy had always had a speculative aspect, as philosophers strove to make sense of the visible cosmos. A deep-seated assumption held by Greek astronomers, that the heavenly bodies moved in uniform, circular orbits, lead to a desire over the centuries to account for or explain away the observed irregularities of planetary motions with their stations and retrogradations. This intention “to save the phenomena,”— that is, to preserve the fundamental circularity—was said to have originated with Plato. While arithmetical schemes had sufficed in Babylonia for such calculation, it was a Greek innovation to devise increasingly complex geometric theories of circular motions (eccentrics and epicycles) in an effort to understand how the sun, moon, and planets moved, so as to place them more precisely in time and space.

Article

Aratus is said to have studied philosophy in Athens, probably coming into contact with Zeno, founder of the Stoic school; subsequently, in 276 bce, he arrived at the court of Antigonus (2) ‘Gonatas’ of Macedon. Little can be independently proven, since the extant lives probably all derive from a single Hellenistic commentator.1Aratus ranks among the finest Hellenistic poets, beside Callimachus (3) and Apollonius (1) Rhodius. He wrote many other works, most of which are lost.2 His sole surviving poem, the Phaenomena, which comprises more than a thousand lines in epic hexameters, describes the positions and motions of the constellations and teaches the reader how to recognize signs of impending weather on earth. The Phaenomena is written in an idealized version of the Archaic language of Homer and Hesiod, and contains mythological material in the form of aitia for some constellations.3 It falls into two parts, the ‘.

Article

Hypsicles of Alexandria was a Greek mathematician and astronomer who flourished around 190 bce. Two of his works are known to us: the first sets out a linear arithmetical scheme for computing the rising times of zodiacal signs (ascensions) and the second is a continuation of Euclid’s Elements which became known as Book XIV. The latter work contains a detailed study, in eight propositions and various lemmas, of the comparison between a dodecahedron and an icosahedron inscribed in the same sphere. This work was close to Euclid’s work in style and format and, because of this, became a part of the textual tradition of the Elements.Hypsicles, of Alexandria (1), mathematician and astronomer (fl. c.190bce), wrote:(1)Book XIV added to Euclid’s Elements. This contains interesting propositions and historical information about relationships between the regular dodecahedron and icosahedron inscribed in the same sphere.(2)On Rising Times.