Native American astronomyAnthony F. Aveni

Citation: Physics Today 37, 6, 24 (1984); doi: 10.1063/1.2916269View online: https://doi.org/10.1063/1.2916269View Table of Contents: http://physicstoday.scitation.org/toc/pto/37/6Published by the American Institute of Physics

Articles you may be interested inAtomic physics with synchrotron radiationPhysics Today 37, 34 (1984); 10.1063/1.2916270

Native American astronomy

Maya Venus ephemeris. Pictured here are facsimiles of two pages of the Dresden Codex, a Mayan book made ofpainted bark parchment. Time flows from left to right. Intervals between observable celestial events are recorded at thebottom, while the dates of occurence of these events in the 260-day ritual count are tabulated in the top 13 rows. At thebottom of each page are four two-digit base-20 dot-bar numbers, with each pair of digits arranged vertically. With eachbar representing 5, each dot representing 1, and the blimp-shaped symbol as a place filler, one can easily read the fournumbers as 236, 90, 250, and 8, the Venus station intervals. The two- and three-digit numbers just below the middle ofeach page are cumulatives of intervals. Just above these numbers are the hieroglyphic symbols of Venus. (Photographcourtesy of the American Philosophical Society, Philadelphia, Pennsylvania.) Figure 1

24 PHYSICS TODAY / JUNE 1984 0031-9228/84/0600 24-09/$01.00 © 1984 American Institute of Physics

Archaeoastronomers are documenting the work of the astronomers ofpre-Columbian America, drawing on such evidence as ancient written ephemeridesand precise astronomical alignments of surviving architecture.

Anthony F. Aveni

Looking into the past, we find culturesvery different from our own, yet wefind people doing many of the things wedo—discovering celestial order throughobservation, developing calendars, cre-ating cosmologies. As scientists, weoften endeavor to explain the unknownby seeking likenesses with known phe-nomena. However, we must be particu-larly careful when we use this strategyto study the astronomy of other cul-tures, for we often become enticed intothinking that their motivations andgoals were the same as ours. Warningof this "presentist" trap in the thick ofthe Stonehenge controversy two de-cades ago, a historian commented thatevery age fabricates the Stonehenge itdesires. Perhaps we gain a measure ofsecurity if we convince ourselves thatprehistoric Newtons and Einsteinswere preaching and practicing ouroutlook millenia ago. But were they?

An eminent Mayanist once casuallydismissed the notion that the ancientinhabitants of Yucatan could havebeen serious mathematicians and as-tronomers by suggesting that Mayaastronomy was astrology pure and sim-ple. However, in civilizations such asthat of the Maya, world views featureda close connection between nature andthe divine. In these cultures, religionand ritual behavior were not detrimen-tal to the development of astronomy,but were the vital driving force behindit. Moreover, history teaches us thatthe desire to prognosticate human af-fairs motivated those who laid thefoundation of our own scientific edifice.Astrology lay behind Kepler's drive toknow the precise courses of the planets,and it served also as the principalmotivation of the Babylonians—bothour predecessors in astronomicalscience.

In ancient civilizations there was nobond between technology and the ac-quisition of precise knowledge, and ourwestern notions of scientific progressand man's control over nature appearto have been almost entirely absent.Thus, if we are to gain a clear under-standing of the astronomical pursuitsof those civilizations, we must be pre-pared to view their activity through the

oddly colored glasses of their cultures.An excursion through the basics of

New World archaeoastronomy, a fieldthat has undergone explosive develop-ment this past decade, will show us thatbeyond the mere listing of the objectsobserved and the precision with whichthey were reckoned, there is much to belearned from examining the astrono-mies of other cultures. Research innative American astronomy is particu-larly significant because, until theSpanish conquest, American cultureslay isolated by two oceans from allsignificant outside influence. Thus, wehave a rare chance to learn how peoplein different times and places developeda knowledge of nature. Understandingthis may give us special insight into ourown science.

Archaeoastronomy is the study of theindigenous written and unwrittenrecord relating to the practice of as-tronomy in the ancient world. Thebreaking of ground in this moderninterdisciplinary field began in theearly 1960s with astronomer GeraldHawkins's pioneering work1 on Stone-henge, which rekindled the idea thatthe great megalithic edifice was built toserve as a storehouse of alignments tokey solar and lunar positions at thehorizon. After more than a decade ofdebate between astronomers and ar-chaeologists over the role of astronomyin the design of ancient ceremonialcenters (a confrontation with territori-al overtones), there has emerged in the1980s a spirit of cooperation across thedisciplines that has resulted in theformation of a number of researchteams to which physical scientists havecontributed enormously. A historicalbranch of the American AstronomicalSociety now lists papers on archaeoas-tronomy at the society's national meet-ings, and in the past two years physi-cists and astronomers have contributedto three international meetings on thesubject.

A developed system of astronomy canbe characterized by the systematicgathering, classification and storage ofprecise astronomical data accompaniedby the creation and refinement of amethodology for reaching importantfuture dates—what we would call acalendar. We expect to find such as-tronomy among high civilizations,

which need uniform time systems todelineate formally the timing of festi-vals, planting and the payment oftributes. The time base maintained bya developed state allows the collectionof astronomical observations and therecognition of the periodicities neces-sary for setting up a calendar. More-over, an organized society usually de-velops a means of transmittingacquired knowledge about the heavens,often through a written record. Thistells us where to look to find developedastronomies in the Americas: amongthose civilizations that by all definitivestandards achieved a high state ofdevelopment—the Mayas and Aztecs ofMexico, and perhaps the Incas of Peru.

This article is an introduction tonative American astronomy. Pre-Co-lumbian astronomers were active inSouth America, Central America,Mexico and North America. It is notpossible to cover all their activity indetail in one short article and stillillustrate the depth of current researchin the field. Therefore, we will devotemuch of our discussion to one example,the Maya of Mexico, a group whoseastronomical activity is rather welldocumented. First, we will look at theMaya written record, which includes avery accurate Venus ephemeris. Thenwe will survey the architectural re-cord—the astronomical alignments ofsurviving structures. We will go on totake a brief look at North AmericanIndian astronomy, on which much re-search remains to be done. Finally, wewill discuss some implications of thegrowing recognition that the key tounderstanding an astronomy is under-standing the cultural context in whichit is practiced.

Mesoamerican written recordPerhaps what excites us most about

the ancient Maya of Mesoamerica (thelatitudes of eastern Mexico that in-clude the Yucatan) is that in addition tocreating monumental architecture andexquisite sculpture and painting, theyalso had developed a system of writingand numeration. When we examinethe handful of books (see figure 1) that

Anthony Aveni is Dana Professor of astron-omy and anthropology at Colgate University,in Hamilton, New York.

PHYSICS TODAY / JUNE 1984 25

Temple of the Sun, one among many buildings at the ruins ofPalenque. Located on the fringe of the rain forest of Central

America, this ceremonial center, erected about 600 AD, displaysnumerous calendric references linking the lives of rulers buried there

to the occurrence of astronomical events. Inset: Calendricinscriptions on a tablet inside the building. (Photographs by Horst

Hartung.) Figure 2

survived the Spanish conquest and thescores of carved monuments that theMaya once displayed publicly in cere-monial centers such as Tikal and Pa-lenque (figure 2), we discover a gram-mar like our own and a syllabarycomposed of more than 800 hiero-glyphs. Some of these symbols repre-sent astronomical objects and concepts.The symbol for Venus, for example,appears in figure 1.

Epigraphic studies shortly after theturn of the century23 revealed that theMaya had a numeration system withplace-value notation and a concept ofzero. Though we might be frightenedaway by the grotesque-looking pictorialaccompaniments to the dot-bar numer-als and hieroglyphs that appear in theMaya calendar of figure 1, a penetrat-ing look at the page reveals that, likemost Maya documents, astronomybears its presence behind the veil ofritual. Adjacent to the Venus table inthe Dresden Codex, or manuscript,named after the city in whose library itturned up three centuries after theconquest, is an ephemeris that givesthe dates of solar and lunar eclipses.

The Maya achieved the eclipse algo-rithm by grouping lunar phase countsin clusters of 6 and 5, defined canonical-ly as 177- and 148-day periods. Appar-ently they realized from long exper-ience that it was only after certaincombinations of such period-clustersthat visible eclipses did indeed occur.Interestingly enough, the Maya

mapped out the entire eclipse programfor the future with neither knowledgeof nor interest in the concept of thenodes of the lunar orbit or the 19-yearnodal regression period that has beengiven so much attention in megalithicastronomy of the Old World, where it issaid to have been detected in thehorizon extremes of the rising andsetting moon.4 Instead, Maya astron-omy gives the appearance of an almostpurely temporal affair that made nouse of orbits, heliocentrism or geocen-trism—or indeed any centrism. Boththe eclipse and Venus tables in theDresden Codex contain only numbersand cycles that churn together like somany interlocking odometers to giveforth predictions.

Precise Venus calendar. A closer lookat the Dresden ephemeris may helpclarify the Maya astronomical system.The table, which is recyclable, is 37 960days long (about 104 years), a numberthe Maya undoubtedly chose because itis a multiple of the 584-day intervalbetween successive conjunctions of Ve-nus and the Sun, a 260-day Mayanritual count generated by matching 13numbers with 20 named days, and the365-day approximation to the tropicalyear. The Maya were especially awareof the 8:5 ratio between the lengths ofthe Venus and Earth years, a discoveryrevealed to them through observationof the 8-year seasonal recurrence ofVenus phenomena. Our way of classi-fying the planets heliocentrically

might lead us to lose sight of the specialrelationship in the sky between theSun and Venus that the Maya seem tohave emphasized. Unlike all the otherplanets (save Mercury), Venus followsclosely upon the course of the Sun,never deviating by more than 46° fromthe Sun's position. Thus, the planetappears as the evening star in the westafter which it is blocked by the Sun.During this period of blockage, knownas inferior conjunction, Venus passesin front of the Sun. Then, one viewsVenus as the morning star in the east,before sunrise, only to find it disappear-ing into the Sun once again, this timeby passing behind it.

The planet's pre-dawn heliacal rise,or first appearance after invisibilitydue to conjunction with the Sun, issymbolized by the apparition of Kukul-can, the god of Venus. Kukulcan is aman-god who, like the visible aspects ofVenus, symbolizes the cyclic myth ofdeparture and return (or death andresurrection) in the Maya world view.Indeed, in central Mexico the Aztecsconfused Cortez with the returningQuetzalcoatl, their version of Kukul-can, whose return they anticipatedprecisely at the time of the Spanishinvasion. Kukulcan is shown in themiddle panel of each page of the Venustable flinging spears or dazzling rays oflight—evil omens—at victims depictedin the lower panels. The rays representthe incipient light of the resurrectedgod who had previously absented him-

26 PHYSICS TODAY / JUNE 1984

self from view. Evidently, the reap-pearance of Venus in different quartersafter a prolonged absence carried var-ious evil connotations for the people ofYucatan.

At the bottom of each page of thetable (such as the pages shown in figure1) we find Venus's 584-day synodiccycle broken down, not into the periodswe would expect from reading one ofour own astronomy texts, but ratherinto periods corresponding to the plan-et's four celestial stations describedabove. Venus is said to spend its 584days as follows, with the actual meanperiods given in parentheses:• 236 days as the morning star (263days)• 90 days in the disappearance inter-val at superior conjunction (50 days)• 250 days as the evening star (263days)• 8 days in the disappearance intervalat inferior conjunction (8 days).It is after the 8-day disappearance ofVenus that the Venus god Kukulcanrises heliacally and flings his spears oflight, thus casting evil upon Earth.

At first glance these numbers mightlead us to conclude that the Maya weretotally incapable of pinning down thegreat luminary. How else could theymisclock one of the disappearance in-tervals by more than a month? Butlooking more closely at the calendar wediscover that, like so many othernumbers that appear in the Mayainscriptions, these intervals are con-trived to blend with other numbers; forexample, 236 days is 8 lunar months.

Whether this fact reveals a Mayaattempt to relate Venus and lunarcycles in concrete observational terms,scholars cannot say at this stage. How-ever, it seems very likely that onemotive behind the selection of thesedeceptive-looking numbers lay in aritual constraint that was built into thecalendar. The Maya believed that onlycertain of the 20 named days thatrepeat to make up the 260-day cyclecould be used to celebrate the transi-tion of the planet from one celestialstation to the next. This notion resem-bles our calendric habit of insistingthat Washington's birthday be cele-brated on a Monday even if that day isnot the real anniversary of the event.

Examining these named days, whichappear written across the table in 13horizontal lines at the top of each page,historian of science Sharon Gibbs hasargued5 that the canonic intervalsprobably were chosen to guaranteecelebration of the Venus appearanceclosest to but not before the planet'sactual first appearance. In fact, sheshowed that the tabulated intervalslink specifically designated ritual datesoccurring as close as possible to theevents of last and first visibility with-out actually ever occurring during

disappearance. Indeed, such a ritualconstraint would have placed a taxingburden upon the astronomer, for notonly would he have to observe andrecord celestial events, but he wouldalso have to worry about displaying hisdata in such a fashion that it exhibitscertain commensurabilities with re-spect to non-astronomical cycles ema-nating from another quarter.

Paradoxically, even though Mayachronologists seem to be bowing toritual by falsifying short-term Venusevents, current research indicates thatby the middle of the 10th century theyhad developed a correction scheme tokeep Venus's canonic 584-day cycle ofevents on track with its true synodicperiod of 583.92 days. Expressed in ourterms, the scheme, which called for theperiodic omission of certain segmentsof the count, was accurate to 2 hours in481 years. Such accuracy exceeds allattempts up to the Gregorian reform ofour own calendar to keep an accurateaccount of the annual solar cycle.

Mesoamerican architectural recordGiven such a precise calendar, we

wonder: What observations are neces-sary to predict the heliacal rise ofVenus, and is there any evidence in thesurviving record about the modus oper-andi of Maya astronomy? Unlike theBabylonians, the Maya appear to haveleft us no observing logs or "notebooks"

delineating a record of their sightings.The codices seem to represent only thefinished product—the public side oftheir science.

An important clue lay hidden for along time in the standing architecture.The last decade of Maya research hasshown that many structures arealigned toward astronomical eventsoccurring at the horizon. A Spanishhistorian tells us quite specifically thatin ancient Mexico City, King Mocte-zuma wished to arrange his principalAztec temple so that the Sun would riseover the middle of it at the equinoxes,and that when the architects failed intheir first attempt, they were forced totear it down and straighten it! Such anact should come as no surprise once weunderstand Aztec and Maya ceremon-ial centers as places for the perfor-mance of important rituals. Moreover,it is reasonable to anticipate an empha-sis on horizon alignments in the astron-omies of people living in tropical lati-tudes. In the higher latitudes, diurnalmotion clearly involves circulationabout a pole. Celestial objects near thehorizon move sideways as well as upand down as they rise or set. However,in tropical skies stars rise and set alongtracks that are nearly vertical withrespect to the horizon, making it easyfor equatorial observers to classify di-rections on Earth by celestial referencepoints.

Caracol of Chichen Itzd, Yucatan, Mexico, a 10th-century Mayaobservatory. Sight lines through various openings are believed to have

marked the horizon extremes of Venus.(Photograph by Horst Hartung.) Figure 3

PHYSICS TODAY / JUNE 1984 27

The precise time and place of the lastvisibility of Venus at the westernhorizon (before the planet moves infront of the Sun) constitutes an index ofthe length of time that the planet willremain obscured by the Sun duringinferior conjunction.612 Therefore, wemight expect that any Venus watcherin the tropics would set up horizonalignments to the west. Also, we mightanticipate observation of the planet'shorizon standstill positions. We findthat while these horizon extremes oc-cur on an annual basis as Venus movesmore or less with the Sun, a seasonalcycle of great extremes repeats almostexactly after an 8-year interval, whichis a period given considerable attentionin the Dresden Codex.

At Chichen Itza, the Maya, aftertheir tenth-century AD conquest by theToltecs, preserved precisely these Ve-nus orientations in the Caracol, theround building shown in figure 3. TheCaracol was erected about the sametime the Dresden Codex was written,and is said to have been dedicated tothe Venus god Kukulcan. Using sur-veyor's transit and astronomical fix,architect Horst Hartung, Sharon Gibbsand I found that a pair of diagonals inthe windows of the turret, and anotherpair of alignments in the base of thebuilding, point to within V̂ 0 on theaverage of the places where Venus setover the western horizon at southerlyand northerly standstills around 1000AD, when archaeologists tell us thebuilding was completed. More impor-tantly, the origin of the Dresden Codexcan be placed both in space and timequite close to Chichen Itza. Thus, it isnot too large a leap to suggest that theCaracol was the very astronomicalobservatory that lay behind the writtenVenus calendar.

Many aligned structures. Other build-ings in Yucatan aligned to Venusinclude the Palace of the Governor atUxmal. Its long facade and principaldoorway face 28°05' south of east, whichis within 2 minutes of arc of thesoutherly standstill position of Venusin 750 AD, when the palace is thoughtto have been built. Moreover, theentire structure, which was built on anartificial mound 400 meters on a side, ismis-aligned by 20° with respect to theother buildings at Uxmal, thus empha-sizing its special nature and lendingsome force to the astronomical hypoth-esis. The principal pyramid at theruins of Nohpat, a 25-m-high structure,is the only visible feature from theGovernor's doorway on an otherwiseflat horizon. It bears 2813' south ofeast at a range of 6 km, or just 15 m offthe perpendicular. Moreover, this pyr-amid accurately marked the "turn-around" point in the 8-year Venuscycle, which occurred at 28°03' south ofeast.

Just as archaeological data rein-forced the hypotheses of astronomicalorientation both at Chichen Itza andUxmal, so too iconographic evidencecomes to the aid of astronomy at theGovernor's Palace. Close inspectionreveals that the cornice of the buildingis adorned with over 300 Venus glyphscarved in stone—the same ones thatappear in the Venus table of the Codex.Also, the figure of a Maya rain god thatappears at the northeast cornerstone ofthe building displays on its foreheadthe number eight—3 dots suspendedfrom a bar—which may signify Venus's8-day disappearance before heliacalrise, or perhaps its 8-year cycle.

The use of the surveyor's transit tocollect data on the astronomical orien-tation of sites in central Mexico hasrevealed the interesting fact that allthe sites are skewed clockwise from thenorth (looking down from above). Thishabit probably arose from a traditionestablished at Teotihuacan, the mostexpansive and influential site in all ofMexico, which flourished about thetime of the beginning of the Christianera. Signs of Teotihuacan forms ofpottery and architecture are found allover Mexico and Central America, in-cluding Maya Yucatan. At Teotihua-can, located near Mexico City, we findboth a cardinal grid plan, that is, a gridoriented north-south and east-west,and a plan skewed to align with horizonevents that may involve the Pleiades, agroup of stars of central importance inMesoamerican star lore. An equinox

North

alignment discovered in the 15th-cen-tury Aztec ruins of Tenochtitlan alsohas been documented at Teotihuacan1500 years earlier, thus suggesting along astronomical tradition.

At the ruins of Alta Vista (nearChalchihuites, Mexico) we find evi-dence that colonists from Teotihuacanhad attempted to find where on Earththe Sun turned around, that is, thetropic, where the Sun rises to thezenith at noon only for a day, and thenreturns to the south of the zenith forall other days of the year. We wouldidentify the day as the June solstice.At Alta Vista, which is very near thetropic of Cancer (see figure 4), and atTeotihuacan we find identical petro-glyphs carved in stone and in the floorsof buildings to mark significant align-ments. These symbols, of which morethan 50 are known throughout Mexico,usually appear as a double circle cen-tered on a cross. The curious design,shown in figure 5, is made up of holeshammered into stucco or rock with apercussive device.

These discoveries may indicate awidespread organized attempt to insti-tute calendric principles on a "nation-wide" basis. However, we sense that atleast among the Maya, astronomy stillwas governed by a ritual elite whosesecret methods and knowledge werenot shared with the man in the field.We can only wonder whether an esoter-icism of advanced astronomy and aconsequent detachment between rulersand people might have contributed to

Double alignment scheme at the ruins of Alta Vista on the Tropic ofCancer. From a cardinally-oriented Sun temple to the conspicuous

peak of the mountain Cerro Picacho one views the equinox sunrise.The June solstice sunrise is visible over Cerro Picacho from a pair ofpecked circles (each like the one shown in figure 5) on a plateau just

south of Alta Vista. In 650 AD, when Alta Vista was founded, thetropic was only about 14 miles north of the site. (Diagram by Horst

Hartung.) Figure 4

28 PHYSICS TODAY / JUNE 1984

Plan of Teotihuacan (near Mexico City) and possible surveyor's mark. Often the grid plans of entire cities were skewedout of line with the natural landscape in order to point to important astronomical events at the horizon. In this case, thenorth-south and east-west axes of Teotihuacan are marked by sets of pecked circles (right). The E-W axis 15°21' N ofW is directed to the setting position of the Pleiades, which underwent heliacal rise on the day of solar zenith passage.(From reference 6.) Figure 5

the precipitous collapse of the Mayacivilization on the eve of the Spanishconquest of the Americas.

North American Indian astronomyWhat of the rest of the Americas?

While the civilizations of Mesoamericahave left us a relatively abundantcorpus and a great variety of usefuldata, the cultures of the Andes remainyet alive. For example, ethnologistsworking in remote regions of the Andesoffer evidence that contemporary peo-ple, descendants of the ancient Inca,know the same constellations and di-vide the space of their city according tothe same solar observations at horizonmade by their ancestors. Nevertheless,the question of the nature and practiceof astronomy among the indigenouscivilizations of North America presentsproblems. Our predecessors on thecontinent were almost totally sub-merged by the tidal advances of Euro-pean culture. Nevertheless, archaeoas-tronomy on the North Americancontinent has developed considerablyin the past decade and a half. Ar-chaeoastronomers have made particu-lar progress in understanding the con-nection between ceremonialism andcalendar, as evidenced by the manyreports on work in this area at recentconferences at Oxford7 and Santa Fe.8

Most of the recent studies involvesolar motion, but earlier findings indi-cate the possible recording of the 1054AD supernova in native rock art, andthe possible astronomical use of theMedicine Wheel of the Big Horn Moun-tains. This spoked circle, shown infigure 6, was fashioned out of largeboulders some time after the 12thcentury. Astronomer John Eddy wasthe first to note9 the wheel's possible

use as a device for timekeeping.Eddy offers a tight argument by

illustrating a coherent alignmentscheme. Alignments about the hub ofthe wheel point not only to the positionof summer solstice sunrise, but also tothe rising positions of three bright starswhose heliacal risings occur both atintervals of a lunar month and at timesthat mark each of the three months ofthe year that are warm enough for thesemi-sedentary people who built theMedicine Wheel to occupy the Big HornMountains. Thus the wheel may haveserved to warn of the approach of coldweather.

The idea of employing one set ofobservations as a check on another, inthis case the heliacal risings of starsand lunar events, is similar to but lesscomplex than the Maya scheme de-scribed above for interrelating timecycles. Careful reflection reveals thatthe Inca of South America used thesame method when they created anagricultural calendar that correlatedtheir lunar months with both theseasonal year and events associatedwith the celestial course of the Ple-iades. Thus, the Inca orientation sys-tem and the North American MedicineWheel both served to relate solar, lunarand stellar periods by direct observa-tion; that is, both were calendars free ofcalculation. We know that the MooseMountain Medicine Wheel in Saskatch-ewan has a similar layout, but whatabout the others? There are over threedozen medicine wheels in the RockyMountain area that still need to belooked at.

Other astronomical orientationschemes uncovered in North Americasuggest a concern with precision inmarking the time of year and an

interest in relating geometry and as-tronomy. Physicist Ray Hively andphilosopher Robert Horn, both of Earl-ham College in Indiana, have shown10

that the prehistoric earthworks ofNewark, Ohio, are laid out very accura-tely and have solar and possibly lunaralignments.

Casa Rinconada, which dates fromthe 11th-century Anasazi-Pueblo cul-tures of Chaco Canyon, New Mexico, isa giant circular "kiva," a structureintended for worship. It is perfectlyaligned on the pole star and has aspecial window that may have beendesigned to admit the light of summersolstice sunrise, as the sketch in figure7 indicates. The structure very likelyhad a 28-niche counting device builtinto it. Incidentally, the number ofspokes on the Medicine Wheel also is28, which may represent a count of thedays on which the moon is visible.

At Fajada Butte, also in Chaco Can-yon, light enters slit-like openingsbetween a set of vertical slabs, possiblysituated intentionally, and falls upon acarved spiral petroglyph in a partiallydarkened chamber. The elongatedlight spot, the movement of whichreflects the course of the Sun, may haveserved to mark the equinox at noon andto indicate other times of the year aswell. However, the apparent unique-ness of the device and the absence ofother archaeological remains at thesite suggest the need to search for otherexamples before we assign this oneundue importance. In a huge adobestructure located in Casa Grande, Ari-zona, investigators have found accu-rate solar alignments at solstices andequinoxes. Here the light entersthrough horizontal portals arrangedin rows high along the western wall

PHYSICS TODAY / JUNE 1984 29

of the structure.In Von Del Chamberlain's study11 of

the Skidi Pawnee of what is nowcentral Nebraska, we find that evenhabitation structures may have func-tioned as observatories. Chamberlainfinds that the standardized orientationand architecture of the earth lodges inwhich the Pawnee lived highlight anumber of celestial phenomena, rang-ing from the movement of the solardisk to that of constellations known tohave been named. An unusually richrecord on star myths among thesepeople aids our understanding of theirideas about astronomy.

The Chumash Indians of Californiaalso had a great deal of interest inastronomy. Their astronomical record,which includes the sighting of comets,appears in the rock art of that area aswell as in a handful of accompanyingsites with solar alignments.

As the reader can see, evidence onthe practice of astronomy in pre-Co-lumbian North America is fragmen-tary, but fortunately it has begun toreceive serious attention by a largernumber of American astronomers. In-terestingly, we have learned that manymodern observatories are located in thesame places that our native Americanpredecessors were most active. Per-haps "long-eyes," as the Pima Indianscalled the astronomers at Kitt PeakNational Observatory, gravitate to-ward the same observing grounds!

Context reveals meaningThe sky presents all of humankind

with a set of universals; everywhere theSun rises and sets, attains its horizonextremes and participates in eclipses.Thus, the sky becomes a laboratory fortesting the question: Do all culturesreact in the same way to the phenom-ena that pass before our eyes? How-ever, interpreting reactions is not sim-ple, and archaeoastronomers confronta problem that faces all students ofantiquity: Have we exaggerated thedegree to which ancient people thoughtlike us? We can avoid the pitfall ofcreating false images of ourselves inthe past only by gaining a broadknowledge of the people whose astron-omy we study. We must know abouttheir religion and ritual, their art andsculpture, even the organization oftheir families. For the researchertrained in the physical sciences, aserious venture into archaeoastronomyrequires a substantial commitment,but the experience of learning aboutanother culture's view of nature can bevery rewarding.

In the case of British megalithicastronomy, which inspired the rebirthand expansion of interest in ancientNew World astronomy, it is no easytask to understand the astronomy interms of the culture. The stone age

Medicine wheel of the Big Horn Mountains, Wyoming, and itsaccompanying alignments. The diameter of the wheel is about 90 feet.

There are 28 spokes. (USDA Forest Service photograph. Diagramfrom John A. Eddy.) Figure 6

Britons left us no written record, scantart works and only a few archaeologicalremains. Indeed, we have little morethan the alignments to work with. Ifwe are to believe in the astronomicalinterpretation of Stonehenge, not onlydo we need to establish that theclaimed accuracy of the alignments ispresent in the standing stones, but wemust also explain why these peoplewould share with us the same penchantfor precision. There is no doubt thatearly hunter-gatherers, semi-sedentarypeople who might convene for a time ata communal center such as Britain'sStonehenge or Wyoming's MedicineWheel to trade or worship, would desireto mark events in time. We might wellexpect them to track the Sun and Moonand, perhaps, the bright planets.Alignments to the rising and settingpoints of astronomical objects makesense, given the sphere of inquiry ofthese people—but would they really

care to measure the 9-arc-minute lunarwobble, as some proponents of theastronomical interpretation have sug-gested?

Those who ask us to believe thatthese stone-age people, captivated bythe finer details of lunar motion, andpossessing the time to reflect uponesoteric matters, pursued knowledgefor its own sake, are asking us to jointhem in the assumption that the an-cients thought as we do. It may beromantic to think of our predecessorsin this way, but our engineering doesnot make engineers of them nor do ourcomputers make computing devices oftheir artifacts.

With a growing recognition that thecultural context holds the key to under-standing ancient astronomy, NewWorld archaeoastronomy has begun toflourish as evidence from ethnology,epigraphy, archaeology and mythologyhas joined the alignment data. One

30 PHYSICS TODAY / JUNE 1984

lesson we learn from the interdisciplin-ary study is that things often turn outto be different from what we mighthave anticipated. For example, therebuilt Aztec structure at Tenochtitlanto which we referred earlier is orientedprecisely to the equinox sunrise eventhough it is misaligned with the east-west line by 7°. Only the writtenevidence tells us that the skew was dueto the fact that the observation wasmade over an elevated surface, so thatthe Sun was observed only after it hadmoved some distance along the slantedpath on which it rises. This exampleillustrates how far we may be fromarriving at the truth if we follow thesimple research path that isolates as-tronomy from the context in which itactually was practiced.

Was it science? Finally, we will allwonder: Is it correct to call the practiceof the ancients scientific astronomy?Asger Aaboe, a historian of Old Worldscience, gives13 us one of the mostexplicit definitions of scientific astron-omy. He defines an astronomical the-ory to be scientific only when it

gives us control over the irregulari-ties within each [astronomical] pe-riod and thus frees us from con-stant consultation of observationrecords.

Such a theory is, essentially,a mathematical description of ce-lestial phenomena capable of yield-ing numerical predictions that canbe tested against observations.

Aaboe uses as examples Babylonianlunar texts from the Seleucid Era. Itcan be shown that the precise positionsof solar and lunar conjunctions given inthese texts could not have come fromdirect observations but rather musthave derived from the application ofcertain purely mathematical functionsthat Babylonian astronomers had de-veloped. Aaboe distinguishes scientificastronomy from the less advancedprimitive astronomy, which is a kind ofpassive pastoral activity of recognizingconstellations and marking the appear-ance and disappearance intervals ofplanets as evening or morning stars—the sort of celestial behavior to whichone assigns certain "rustic tasks."

This definition, should we press it,can be fulfilled to varying degrees bythe cultures we have examined. TheMaya, with their precise Venus warn-ing table, would score high; the Chu-mash of California, perhaps somewhatlower. But what does it mean to ask ofevery astronomical pursuit: Is itscience? One can argue that Aaboe'sdefinition is culture-laden, specifically,that his standard of science is the resultof over 3000 years of evolution along aparticular path, during which elementsof culture that affect our definition ofscience have changed. That evolution-ary process included the rise of the

Greek ideal and the industrial revolu-tion, to mention but two importantdevelopments that influenced thecourse of western science. Have we anyreason to expect other people to thinkas we do if they did not evolve along thesame cultural lines? From this point ofview, to ask "Is it science?" is almost toask if it is the product of westernculture.

There is no space here even tosummarize the abundant literature onthe contrasts between traditionalmodes of thought and western science;the differences appear to be vast. Forexample, as Cornell anthropologist Bil-lie Jean Isbell has suggested,14 thesystems of classification that underliewestern science seek similaritiesagainst backgrounds of differences; westrive for causal explanations. On theother hand, Native American thoughtsystems seem to be organized around adialectic that stresses simultaneousinterdependence and contradiction.Applied to astronomy, this principle

argues that, for example, Andean as-tronomical phenomena are perceivedonly as dual pairs, such as the zenithsunrise and antizenith sunset align-ments, which were prominent in thestructure of Cuzco, capital of the Incaempire (figure 8).

An awareness of the vast differencesbetween western and traditional modesof thought will lead us to ask differentquestions. Among some indigenouspeople of South America, a woodpeck-er's beak applied to an aching tooth issaid to provide the cure. We might ask:How can a bird beak effect a cure?However, as anthropologist ClaudeLevi-Strauss commented,15

The real question is not whetherthe touch of a woodpecker's beakdoes in fact cure toothache. It israther whether there is a point ofview from which a woodpecker'sbeak and a man's tooth can be seenas "going together" (the use of thiscongruity for therapeutic purposesbeing only one of its possible uses),

Pueblo Indian klva Casa Rinconada, Chaco Canyon, New Mexico.This semi-subterranean place of worship is accurately aligned to the

pole star. (Drawing by Snowden Hodges, courtesy of Ray Williamson,reference 8.) Figure 7

PHYSICS TODAY / JUNE 1984 31

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Inca masons at Cuzco, as pictured in a 16th-century Spanish book16

about the Inca. The Inca built suntowers to mark the course of theSun at the horizon. This allowed formalization of graded plantingdates for different altitudes in the vertical environment of theAndes. Figure 8

and whether some initial order canbe introduced into the universe bymeans of these groupings.

Perhaps we are finally beginning to aska few correct questions about NativeAmerican astronomies.

References

1. G. Hawkins, J. White, Stonehenge De-coded, Delta Dell, New York (1965).

2. S. G. Morley, An Introduction to theStudy of the Maya Hieroglyphs, Bur.Am. Ethnol. (Smithsonian Inst.), no. 57(1915).

3. J. Teeple, Maya Astronomy, Carn. Inst.Wash., Washington, D.C. (1930).

4. A. Thom, Megalithic Lunar Observator-ies, Oxford U.P., London (1971).

5. S. L. Gibbs in Native American Astron-omy, A. F. Aveni, ed., U. of Texas P.,Austin (1977).

6. A. F. Aveni, Skywatchers of AncientMexico, U. of Texas P., Austin (1980).

7. A. F. Aveni, ed., Archaeoastronomy inthe New World, Cambridge U.P., Cam-bridge (1982).

Circle number 17 on Reader Service Card

8. R. Williamson, ed., Archaeoastonomy inthe Americas, Ballena Press and U.Maryland Center for Archaeoastron-omy, Los Altos, Calif. (1981).

9. J. Eddy, Science 188, 1035 (1974).10. R. Hively, R. Horn, Archaeoastronomy,

number 4, supplement to J. Hist. Astro.13 (1982). page SI.

11. V. D. Chamberlain, When Stars CameDown to Earth, Ballena Press and U.Maryland Center for Archaeoastron-omy, Los Altos, Calif. (1982).

12. A. F. Aveni, Science 213, 161 (1981).13. A. Aaboe, Phil. Trans. Roy. Soc. (Lon-

don) A276, 21 (1974).14. B. J. Isbell in A. F. Aveni, G. Urton, eds.,

Archaeoastronomy & Ethnoastronomyin the American Tropics, New YorkAcad. Sci., New York (1982).

15. C. Levi-Strauss, The Raw and theCooked, Harper & Row, New York(1969).

16. F. Guaman Poma de Ayala, El primernueva corbnica y buen gobierno [1584-1614], Travaux et memoires de l'lnsti-tute d'Ethnologie 23, Universite de Par-is, Paris (1936). •

32 PHYSICS TODAY / JUNE 1984