One of the most famous shadow-and-light phenomena concerns a petroglyph situated toward the summit of Fajada Butte, in Chaco Canyon (see FAJADA BUTTE SUN DAGGER). A carved spiral hidden away behind three slabs of rock leaning against a vertical rock face is occasionally lit up by the light of the sun shining through cracks in the rocks in front of it. Around noon on the summer solstice, however, a thoroughly distinctive dagger of light suddenly appears and bisects the carving. How should this be interpreted? Assuming that the slabs were carefully placed rather than falling into their positions naturally (and there has been some debate on this issue), it appears that a good deal of care was taken in positioning the spirals so that the summer solstice, and possibly other times of the year also, were clearly marked. The location is difficult to access but good for astronomical observation. Comparisons with the practices of historic Pueblos suggest that it might have been a sun shrine—a sacred place where a sun priest came to deposit offerings at certain important times in the ceremonial year. In this sense it would have been far more than a simple calendrical device. It was more likely something that, through its powerful symbolism, helped to affirm the sacredness of this inaccessible place, and by so doing helped to reinforce the power of the person or people who understood its meaning and had the privilege of using it.
As with astronomical alignments, we again encounter a methodological problem: just because we observe a shadow-and-light phenomenon does not mean that it was intended by the builders or had any special significance before our “discovery” of it. Given any pattern carved on a rock, what are the chances that the sun will play across it at some time, quite fortuitously, creating an unintentional effect? In the case of the Chaco petroglyph, more secure interpretations can only stem from wider evidence about Anasazi culture, perhaps with valuable clues from historic and modern Pueblo groups.
A different form of shadow-and-light phenomenon has been noted in Mesoamerica: the so-called zenith tube. ZENITH TUBES are vertical tubes incorporated in specialized ceremonial structures that marked the biannual passage of the sun through the zenith at noon, at which time sunlight could pass directly down the tube and light a chamber below. One of the most impressive examples is found at the ruins of Xochicalco in Mexico, where a tube more than five meters (sixteen feet) long opens into the roof of a natural cave artificially extended to form a rectangular gallery with three central pillars. The use of such tubes for the purposes of astronomical observation cannot be established with certainty but seems likely given the known significance of the ZENITH PASSAGE OF THE SUN in Mesoamerica, both from studies of the ancient Mesoamerican calendar and from modern ethnography.
Displays of light and shadow, especially if they occur only infrequently, can be highly impressive. It is easy to see how they could have conveyed symbolic power, reinforcing sacred associations that formed part of the fabric of the pre-vailing worldview. Their presence in the archaeological record has the potential to reveal aspects of that worldview to us. The power to impress is conveyed to the modern investigator through direct experience—“being there” and experiencing the event for oneself has proved popular and is useful in generating tentative interpretations. But it also brings dangers. There is considerable potential for us to experience shadow-and-light phenomena that had no significance whatsoever to people in the past.
Great monuments also have the power to impress, none more so than STONEHENGE in England. Over the years it has attracted more than its fair share of theories, from the plausible to the plainly ridiculous. However, the general perception prevails that there was some sort of connection between Stonehenge and the skies, which accounts for its frequent appearance on the front covers of books on ancient astronomy. In the meantime, archaeological excavations have put some of these theories in a more secure context. The bluestone and sarsen circles, constructed around the middle of the third millennium B.C.E., replaced earlier timber constructions built within a circular ditch and bank that had been completed some 500 years earlier. The later stone monument was certainly a place of great power, and the solstitial alignment of the main axis, which all commentators agree was deliberate, represented a shift of several degrees from the earlier orientation. The transformation of the monument from timber into stone, the use of exotic stones from faraway places, and the sheer size and scale of the edifice strongly suggest a process of enriching the ritual symbolism of the site around 2500 B.C.E. to legitimize its place at the center of the cosmos and hence its ultimate power. This transformation probably served in turn to reinforce the earthly power and influence of a social elite. The change in the axis to incorporate the solar alignment was almost certainly part of the same process.
Modern Western science is only one of many frameworks of thought within which people all over the world, from Palaeolithic times to the present day, have gained an understanding of natural phenomena, including what could be seen in the sky. Modern science only seems the pinnacle of intellectual achievement from a Western perspective, and seeing it as such creates a tendency, when trying to comprehend non-Western modes of understanding, to single out particular “advances,” seeing them as steps along the road. From an anthropological point of view, it seems stiflingly restrictive to proceed in this way when we can seek a much broader appreciation of different developments in human thought. This can only be achieved by studying the great many ways in which people have striven to comprehend the world that they inhabit and the many different contexts—physical and social— within which particular developments in thought have occurred. This applies just as much to sky knowledge as to all other knowledge. Above all, we need to recognize the magnificent diversity of human worldviews that has existed through time, and to respect them for what they were and are, even though we will inevitably continue to describe them, and try to make sense of them, in the framework of our own.
Using This Book
The entries in this encyclopedia fall into three categories. First, there are those that elaborate upon some of the key themes and issues relating to ancient astronomy, many of which have been introduced above. They include, for example, LUNAR AND LUNI-SOLAR CALENDARS, PALAEOSCIENCE, and ASTRONOMICAL DATING. Other entries in this category relate to particular objects or phenomena in the sky and their cultural significance (for example, ORION and LUNAR ECLIPSES). Also included are broad definitions and explanations of key concepts (such as ARCHAEOASTRONOMY, COSMOLOGY, and ALIGNMENT STUDIES), brief descriptions of procedures and techniques (for example, FIELD SURVEY and STATISTICAL ANALYSIS), and a few people who have been important in the overall development of the subject, such as SIR NORMAN LOCKYER and ALEXANDER THOM. The second category comprises case studies of a variety of types of human society, from hunter-gatherer groups to urban city-states, and spanning a chronological and geographical range that stretches from Upper Palaeolithic Europe through Polynesia and other remote parts of the world prior to European contact. Though the case studies are far from exhaustive, they have been carefully selected to illustrate particular issues and themes, with an emphasis upon cultures and places that are less well known outside the specialist literature of archaeoastronomy. The final category of entries consists of short, nontechnical explanations of basic concepts like SOLSTICES, HELIACAL RISE, and DECLINATION. At the end of each entry is a list of related entries divided into three parts: themes, case studies, and basic concepts. Straightforward definitions of terms are given in the glossary.