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Early observatories


Archaeoastronomy, a word combination of the fields archeology and astronomy, is the study of pre-scientific peoples relation to the sky as part of their natural environment. As a formal investigation, the field of archaeoastronomy is relatively young, having begun only in the 1960s. It is often known as cultural astronomy to indicate the multidisciplinary breadth of the field and its emphasis on cultural practices and issues rather than on the correctness of ancient observations. Archaeoastronomers, those people who study archaeoastronomy as a profession, are concerned to know what observations were made by an ancient society, who made them, and how those observations were integrated into the societys political life, agricultural or hunting-gathering practices, and civic and religious customs. Thus, the tools of modern archaeoastronomers are as likely to be those of art history, sociology, or linguistics as those of the quantitative sciences, such as computer-processing algorithms, large databases, and statistical inference.


Most pre-scientific peoples developed a cosmology (an explanation of the universe) that explained human existence as seamlessly interwoven into the workings of the universe. This relationship of the part to the whole was usually expressed through symbols and metaphors. A simple, almost universal cosmological principle was captured in the idea of mirroring: events and powers in the sky mirrored those on the Earth; Earth was but a microcosm of the sky. In virtually all Northern Hemisphere societies, for example, earthly dwellings (the tepee, yurt, or igloo) were seen as particularized representations of the larger dwelling that arched high overhead in the heavens to create the celestial vault that rotated around the Pole Star. An actual pole of rotation, extending from Earth to heaven, was a strong element of native North American cosmology. In Inuit cosmology, the superior plane (the mythological equivalent of the sky) was known as the Land Above. Other cosmologies have figured the universe as an endlessly folded ribbon, with Earth in the center fold; as a set of nested boxes; or as a series of interlocking spheres.

Pre-scientific societies held the celestial bodies in great reverence, yet were also on an intimate footing with them. Ancient peoples regarded the sky as inhabited by Sky People, deities, departed ancestors, or simply forces. The Sky People or powers were thought to impose order on chaotic human affairs. At the same time, the sky powers could be solicited and manipulated to serve human goals. Their authority could be invoked to justify the actions of a chief priest or ruler. A moon associated with important periods in the agricultural or hunting cycle could be honored to ensure better food supplies. A desire to place the sky powers in the service of the human agenda may have been the impetus that led pre-scientific societies to take up regular observations of the skiesin other words, astronomy.

Early observatories

Written records are missing for many pre-scientific societies as they turned from noting a single celestial event to making the kinds of repeated observations that could be applied to predict events in their own lives, such as harvesting or knowing when to expect newborns in their animal herds. Many ancient peoples did, however, leave physical signs of their observing activities. Among the most intriguing are the sites that, to a modern eye, seemingly could have been used as very early observatories.

Between about 3500 and 1500 BC, Bronze Age builders in Britain and the northwestern portion of France known as Brittany erected, or marked in the existing landscape, thousands of sites that invite speculation about astronomical use. The most fundamental arrangement consisted of a natural indicator on the horizon, such as a notch in a mountain (the foresight), which was aligned with another, artificially made marking, such as a standing post or stone, or a hollowed-out depression in a rock (the backsight). Because distances of up to 28 mi (45 km) have been measured between foresight and backsight, these common configurations have become known as long alignments. Statistical studies show that few long alignments could have been used to establish the date of a major celestial event, such as a solstice, with certainty. Even a rough approximation, however, would have sufficed for ceremonial reasons such as Sun worship.

The Neolithic builders are better known for erecting stone circles, such as Stonehenge in England. (A henge is an earthen mound surrounded by a low bank and a ditch; wooden or stone pillars may be arranged on the top.) Astronomical opinion is divided over the uses of Stonehenge, but the evidence for its primary use as an observatory is considered weak. Stonehenge was built in three phases over a period of about 400 years, beginning around 1700 BC, and is one of many circles built during this period. It stands on flat Salisbury Plain, in southern England. Because the horizon lacks distinctive features, short sight lines may have been incorporated into the placement of the stones. A ritual figure such as a priest or priestess silhouetted against the rising moon, and framed between two megaliths, would also have been an impressive sight.

Astronomers argue that Stonehenge could have been used to observe the winter solstice, the time when the rising of the Sun is farthest south, and the extreme rising and setting positions of the moon. Its primary purpose seems to have been ceremonial. That a ceremonial structure might have later evolved into an observatory in prehistoric Britain has important implications for social organization, for it suggests that an educated, elite class existed to make the observations and supervise the construction and repair of sites. Those educated observers in turn might have been the forerunners of the Druids of the Iron Age in Britain.

Culturally dissimilar groups in the American Southwest and California appear to have followed observing practices like those used in prehistoric Britain. Oral histories taken from nineteenth century Pueblan informants in the Four Corners region indicate that both horizon observations (that is, long alignments) and wall calendars were used. A standing stone or gouge mark or wall painting did not mark the position of the Pueblan observer; rather, it appeared to be esoteric knowledge held by the priest-astronomer, who simply walked to the same spot every time that observations were to be made. Wall calendars were created as sunlight penetrated an opening in a house or residential cave to fall on the opposite wall. With the use of both horizon and wall calendars, the Pueblans could track the motions of the sun, moon, and stars and, also, events that occurred in the four sacred quadrants of the sky. Many of the estimated 300 tribes living in California before contact with Hispanic traders and explorers, which occurred in the 1760s and 1770s, used similar horizon and wall calendars. Some pre-contact California tribes are thought to have had two calendars: a secular one, known to all, and a secret calendar to guide the timing of sacred rituals.

Simple observing stations that made use of existing sight lines and horizon marks stand at one end of the spectrum of early observatories. At the other end is elite, corporate architecture, such as is found in the northern Yucatan site of Chichn Itz. There, the highly elaborated architecture, with its steeply ascending steps and ornately carved and painted reliefs, reflects a complex union of political power and astronomical knowledge.

Chichn Itz, in Central America, was built over two periods that lasted, in aggregate, from about AD 700 to 1263. Its people were both numerate and literate, creating written works that detailed their astronomical culture. The Maya also had a warrior class, waged war regularly, took captives as slaves, and practiced ritual human sacrifice and bloodletting.

The Mayan calendar and Mayan life were dominated by the sun and Venus, whose astrophysical activities are related to each other in a 5:8 ratio considered sacred by the Maya. The sun was associated with warfare; Venus, a fearful power, was associated with warfare, sacrifice, fertility, rain, and maize. In the 1960s and later, glyphs from Mayan writings were interpreted as showing that raids were undertaken


Cosmology In modern science, the integration of several scientific disciplines in the study of the origin of the universe.

Henge An earthen mound surrounded by a ditch; common in Bronze Age Britain and northern France. Stone or wooden pillars were often arranged on top of the mound.

Solstice A calendric marking of the farthest south or farthest north rising of the sun during the solar year.

during important Venus stations, such as its first appearance as the Morning Star or the Evening Star. These raids have come to be called star war events. The Caracol, a building probably designed as an observatory, and several other important ceremonial buildings at Chichn Itz, such as the Great Ball Court, the Upper Temple of the Jaguars, and the Temple of the Warriors, are fairly precisely aligned to face significant sun and Venus positions.

Mayan interest in genealogy made calendrics (relating to calendars) important. Their basic calendar consisted of two cycles, one of 260 named days and one a year of 365 days, which ran concurrently. Fifty-two years of 365 days each formed the Calendar Round. The Maya developed a system for uniquely identifying every one of the 18,980 days in the Calendar Round. A table in the Dresden Codex, one of three Mayan manuscripts to have survived the Spanish conquest, indicates ability to predict solar and lunar eclipses, as well as the behavior of certain other celestial bodies. At the time of the conquest, these predictions may have been accurate to within a day, rather than to within an hour or minute, as was then possible in Europe with the aid of advanced instrumentation. The Maya, however, did not have the concept of an hour.

See also Seasons.



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Marjorie Pannell