The Origins of the Constellations

Alexander A Gurshtein. American Scientist. Volume 85, Issue 3. May/Jun 1997.

Most of us are familiar with the picturesque images associated with the starry patterns in the night sky: Leo is the great lion, Gemini represents a pair of twins, Taurus is the raging bull and Orion is the mighty hunter. But are the constellations merely pictures? Did ancient peoples place these images in the sky merely for some form of spiritual comfort? Or did the constellations perform a more down-to-earth function for the early skygazers as well?

An ancient star atlas that could provide an answer to these questions has yet to be discovered. Images of the stars, the moon and the sun do adorn rock walls in many parts of the world, but there are no maps of the constellations. Yet this does not mean that prehistoric peoples did not connect the points of light into patterns in the night sky. The absence of hardrock evidence might discourage some investigators from pursuing the subject altogether, but I believe it is a healthy exercise to stretch our imaginations and use reason and the archeological context to come up with some plausible hypotheses. By this route perhaps we can enjoy an adventure into the past and into the minds of ancient peoples.

We know, for example, that the annual movement of the stars across the sky provided a calendar by which ancient hunters and farmers could predict the change of the seasons. Their survival would have depended on knowing when to plant, when to harvest and when the herds would migrate. The ability to recognize star patterns would have provided some simple mnemonics for seasonal change. Thus we might expect that stories incorporating Western mythology, symbology and even numerology could hold some clues.

In this regard, the general tendency of historical cultural transmission to retain names through the generations is useful. This seems to be true of the constellations also, which have held their names with a tenacity comparable to that of place-names on the earth (such as landmarks and bodies of water). Indeed many attempts have been made to rename the 12 zodiacal constellations. (Several Christian authors, including Gregory of Tours, tried to apply the names of the 12 Apostles.) Yet despite all the social and cultural changes over the millennia, the names of the constellations have remained inviolable. The constancy of these designations is clearly significant.

So where do we begin? Modern astronomers recognize 88 constellations in the northern and southern skies, all of which have precise boundaries-they are not merely star patterns. Nearly half of these constellations were recognized only after the time of the Alexandrian astronomer Ptolemy, of the second century A.D. The origins of these modern constellations are documented and will not concern us here. Of those constellations known to Ptolemy, the oldest complete list goes back to about 275 B.C. in the Greek didactic poem The Phaenomena by Aratus. In this poem, Aratus refers to 48 constellations, all of which we recognize today except for the Pleiades and the Bow, which are now part of other constellations. Most of the Aratus constellations are visible to observers at midnorthern latitudes, and it is the history of these constellations-which comprise the modern zodiac, all of the northern sky and much of the southern sky-that will be the subject of this discussion.

Zodiacal Quartets

The sun, the moon and the planets appear to move across the sky relative to the stars along a path known as the ecliptic, a route for eclipses and the track of the sun (via solis in Latin). Thirteen constellations are located along the ecliptic, but only 12 are historically considered to be part of the zodiac. (The giant Ophiucus is the outcast.) The history of these 12 constellations is deeply entangled with the 12 signs of the astrologer’s zodiac, but many of the ecliptic constellations antedate the astrologer’s craft.

Each of the 12 astrological signs extends equally (30 degrees) along the ecliptic to complete the 360 degrees of the zodiacal circle. The oldest known cuneiform texts with 12 equal zodiacal signs date to the 5th century B.C. (van der Waerden 1974), suggesting that the traditional zodiac was established by this time. Earlier records, however, reveal that the signs were not always evenly spaced: Babylonian texts dating to 700 B.C. (such as the Mul.Apin series) contain not equal signs but irregular zodiacal constellations. This discrepancy is a clue that the constellations of the ecliptic may not have been originally conceived as a complete 12-part system. Indeed, some of the zodiacal constellations we know of today were absent at this time.

Why would ancient peoples care to identify certain star patterns along the ecliptic before others? Are the zodiacal constellations merely fanciful images, or do they represent something else? If the constellations had been designed simply as pictures-noteworthy groups of stars-they should consist of bright stars with easily remembered configurations. Certainly there are such constellations: The bright stars of Ursa Major and Orion are glittering examples. But the compositions of many other constellations provide contrary instances: Pisces and Aquarius, which are among the largest constellations, contain no bright stars at all. The historical existence of these dim and unremarkable star patterns suggests that some of the constellations performed some other role-and this may be a clue to their origins.

One of the most obvious observations one can make of the star patterns in the night sky is that they change regularly with the four seasons. Zodiacal constellations that are high in the winter night sky, for example, are lost in the glare of the daytime sky during the summer. Similarly, constellations that are high in the night sky during the spring are invisible during autumn. With a little further study an observer would notice that the sun’s height above the horizon also varies with the seasons. And this is naturally related to the varying duration of daylight and darkness throughout the year.

Systematic observations of the sky would have identified four special days of the year that are related to the movement of the sun: the day that the midday sun is highest over the horizon (the summer solstice), the day that the midday sun is lowest over the horizon (the winter solstice), the day after the winter solstice when the day and the night are of equal duration (the vernal equinox) and the day after the summer solstice when the day and the night are of equal duration (the autumnal equinox).

Could the ancients have been able to deduce which four days of the year these were? Actually it is quite easily done with a vertical rod placed in the ground. The shortest midday shadow in the course of a year occurs when the sun is highest in the sky, marking the summer solstice. Likewise the longest midday shadow occurs on the day of the year when the sun is lowest in the sky, marking the winter solstice. The two equinox points could also be determined easily. A line drawn parallel to the rod’s shadow at midday would mark the midday line. The day that the sun rises at a point on the horizon that forms a line exactly perpendicular to the midday line, marks an equinox. There are two such days every year, one in the autumn and one in the spring.

As the sun makes its annual passage along the ecliptic, early observers might have noticed that the four special days correspond to certain patterns of stars in the sky. In modern times, for example, the sun is passing through the constellation Pisces during the vernal equinox, through Gemini during the summer solstice, through Virgo during the autumnal equinox and through Sagittarius during the winter solstice. The reader can confirm this by noting which zodiacal constellations are high in the sky in the middle of the night on these four days: The sun will naturally be located in the zodiacal constellation that is on the opposite side of the ecliptic circle.

Several thousand years ago, however, a skygazer would not have found the four special points on the ecliptic located in the constellations where they now reside. This is because the earth “wobbles” as it spins on its axis, not unlike the gyrations of a spinning top. This precession of the earth’s axis describes a complete circle in a period of about 26,000 years. One consequence of precession is that the positions of the equinox and solstice points move along the ecliptic. That is, the four distinct points shift westward along the zodiacal constellations. On average, one of these four points passes through a zodiacal constellation about every 2,140 years.

Since the four points move as a rigid system through the ecliptic, the four constellations that mark the points constitute an integral quartet. For the present purposes it is useful to name these quartets after the constellation containing the vernal equinox. Thus the modern epoch corresponds to the Pisces quartet, which began about 100 B.C. and will end sometime after 2000 A.D. (when the so-called Aquarius era will begin-the true beginning of the “Age of Aquarius” in popular culture). The constellations of the earlier quartets can be reconstructed by following the vernal equinox through successive constellations along the ecliptic. Between 2200 B.C. and 100 B.C. the vernal equinox was in Aries, from 4400 B.C. to 2200 B.C. it was in Taurus, and between 6500 B.C. and 4400 B.C. it was in the constellation Gemini. I propose that ancient peoples first recognized these quartets during their respective epochs and that the images that constitute the zodiac were first applied to the constellations at some time during these epochs.

Since the movement of the equinox and solstice points can be extrapolated farther back in history, the reader may wonder why I believe the zodiacal constellations owe their origins to epochs since 6500 B.C. Who is to say that the Cancer quartet, which constituted the four special points on the ecliptic during the 2,000-year epoch preceding about 6500 B.C., was not recognized by the people of that time? I shall argue that the symbolic images portrayed in the zodiacal constellations only make sense in terms of the three quartets and their epochs described below.

The Gemini Quartet

The origin of the term zodiac-which is from the Greek zodiakos kyklos or “circle of animals”-remains unknown. As it is, five of the 12 zodiacal names are not animals: Four are anthropomorphic beings (Gemini the twins, Virgo the virgin, Sagittarius the centaur/archer and Aquarius the water carrier) and one is a tool (Libra the scales). The ancient symbolism attached to the 12 constellations hints at why certain images were chosen to represent the star patterns.

Of the three epochs that immediately antedate the oldest known record of the zodiac, the Gemini quartet (from about 6500 B.C. to 4400 B.C.) stands out because it contains three of the four anthropomorphic constellations (Gemini, Virgo and Sagittarius), and thus constitutes a circle of human-like forms. Anthropomorphic images are relatively common among the artifacts of Neolithic (and older) peoples, so it seems appropriate that such images would be placed in the sky as well.

What are we to make of the Gemini twins marking the vernal equinox? The image of the twins is a common symbol in ancient cultures, and its significance goes back to a general myth about the heavenly twin children of a supreme sun-god (Gamkrelidze and Ivanov 1984). Perhaps Gemini was seen as a pointer for new life, the springtime renewal of nature.

Virgo, which corresponded to the summer solstice point during this epoch, may be a symbol of summertime fertility. The constellation may be a direct descendant of the mother-goddess image that can be found throughout the Near East and Europe, and that was often represented in agricultural societies of the Neolithic as a naked, pregnant woman or a woman giving birth. Indeed the earliest portrayals of the constellation show Virgo holding a spike of grain (hence the name Spica of its most prominent star).

The autumnal constellation of the Gemini quartet is Sagittarius, the centaur with a bow in his hands. Sagittarius may reflect the symbolic movement of the sun: A hunter shoots and wounds the sun, which starts its descent into the “Lower World.”

In winter, the sun is lowest in the sky and appears to linger over the threshold of the Lower World, corresponding to Pisces, the fishes of the Gemini quartet. The cross-cultural link between winter and the concept of a Lower World has been elucidated by the 19th-century British ethnographer E. B. Tyler and many others. Numerous rituals in various cultures indicate that water has long been considered to be an element of the Lower World. The “Land of the Departed Souls,” for example, is situated in the Far West, beneath a watery boundary Similarly, the River Styx of the ancient Greeks was considered to be a basic element of the Lower World. Perhaps the waters of the Lower World had no anthropomorphic images when the quartet was created, and so a pair of fishes served the purpose.

The Taurus and Aries Quartets As the fourth millennium B.C. approached, the precession of the earth’s axis moved the four special points westward along the ecliptic out of the constellations of the Gemini quartet. How might the ancient observers have reacted to this change? It seems likely that the human tendency to retain cultural traditions would not have permitted the obliteration of the Gemini quartet, but it would have become necessary to map new sectors of the ecliptic as places for the four special points. These sectors became the constellations of the Taurus quartet: Taurus the bull, Leo the lion, Scorpius the scorpion and Aquarius the water carrier.

In the third or fourth millennium B.C., when these images were first applied to the Taurus quartet, the sociocultural conditions of the ancient world had changed considerably in the 2,000 (or more) years since the Gemini quartet had been created. The former epoch saw some of the first urban societies, whereas the latter saw the development of religious institutions that were typically led by a priesthood that controlled the cult, the economy and the rituals of the temples. Whereas Neolithic populations often possessed small clay statuettes of anthropomorphic images (hence the human-like forms of the Gemini quartet), the further development of agricultural civilizations led to the use of gold, silver and stone for the fabrication of idols in the form of animals rather than human beings. This transition in popular imagery is consistent with the use of animal figures for three of the four constellations of the Taurus quartet.

The transfer from the worship of a mothergoddess (female) image to a male image at this time may account for the use of a bull (signifying masculine virility) as the symbol for the vernal equinox. (Incidentally, the bull imagery may also have established itself as the golden calf of the Old Testament.) The image of the lion also played a significant role as a symbol of supreme power, and this is consistent with its use for the constellation Leo, which marked the summer solstice, the sun’s highest point on the ecliptic path, during this epoch. The image of a lion tearing at a bull is a common motif in ancient Eastern art, and it has been suggested that the fight between the lion and the bull had a sacred astronomical meaning, marking the calendrical transition from spring to summer (Hartner 1965). During the epoch of the Taurus quartet, the four special constellations did indeed comprise a circle of animals (or zodiac).

Scorpius marks the autumnal equinox during this epoch, and its use is consistent with the metaphor of the previous epoch in which Sagittarius shoots and wounds the sun. In this instance the scorpion stings the sun, which then begins its descent into the Lower World. Here again, a water-based image-Aquarius, the water carrier-represents the winter solstice.

A perusal of the oldest cuneiform texts of the Babylonians (the mul.APIN tablets) reveals that the names of the constellations in the Gemini and the Taurus quartets existed by about 700 B.c. This is not the case with some of the constellations of the next quartet, marked by the transition of the vernal equinox into Aries, the ram. The British writer Rupert Gleadow was among the first to observe that the ram was absent from the Babylonian sky of about 1000 B.C. Consistent with the absence of Aries is the absence of Cancer the crab (marking the summer solstice). Moreover, the Akkadian name for the star pattern in Libra (which marked the autumnal equinox) at this time means “horn of a scorpion” (referring to the claws of Scorpius), suggesting that Libra (as the image of the scales) may not have existed at this time, but was instead part of the constellation Scorpius. Indeed the Egyptian priest Manetho of Alexandria (during the reign of the King Ptolemy I Soter) noted that Libra was separated from Scorpius to mark the autumnal equinox.

The symbolism marking the transition from the Taurus to the Aries quartet is consistent once again with the sociocultural changes in the Near East. The Old Testament warned against the idols and cult statues of Near Eastern temples at a time when monotheism was on the verge of predominating. Artistic images and parables had become widespread in the literature of the era, and it is in this context that the names of the Aries quartet are allegorical, rather than merely symbolic representations of deities. Certainly others have remarked that the epoch of Aries is associated with the biblical story of Moses coming down from Mount Sinai as “two horned,” or crowned with the ram’s horns, while his flock disobediently insisted on dancing around the golden calf, a metaphor for Taurus as the bull (de Santillana and von Dechend 1969).

We can also deduce the significance of the names in the Aries quartet in this era. The ram, for example, is strongly connected with ancient spring rituals. (In the second millennium B.C., the Hebrew patriarch Abraham changed the ritual sacrifice from that of a human being to a ram.) Cancer the crab, as the symbol of summer, can allegorically refer to the reversal of the sun’s motion as it passes the highest point of the ecliptic. Even today the most northerly latitude that the sun can shine directly overhead is named the Tropic of Cancer, suggesting that this term was first applied when Cancer marked the summer solstice point. The constellation Libra, represented by the scales, no longer shoots the sun as did the autumnal constellations of the Gemini and Taurus quartets, but instead it represents the night-and-day balance of the autumnal equinox. Capricornus, the goat-fish, is the apparent heir of the water symbols used for the winter solstice in the earlier quartets.

It was after the introduction of the Aries quartet that the ancients recognized that the 12 constellations comprising the three quartets completed the ecliptic circle, and that this number roughly corresponds to the number of lunar cycles (or months) in a solar year. The 12-part zodiac became complete. In this regard, it should come as no surprise to learn that Aries, marking the vernal equinox of that epoch, is the first sign of the zodiac.

The exclusion of the 13th constellation on the ecliptic (Ophiucus) from the zodiac is consistent with the idea that the zodiac was conceived as comprising three quartets. Furthermore, the notion that the zodiac consists of three quartets is consistent with the symbols during their respective epochs, and with the metaphorical progression of “ascent, height, descent and depth” in each set.

Other Beginnings

At this point I have only discussed the origins of the zodiacal constellations, yet the classical Greeks were familiar with no less than 46 of the constellations we now recognize. Where and when did these other constellations begin? Here I would like to explore some other themes and patterns intrinsic to the constellations that might provide some clue to their origins.

Many have proposed that Ursa Major (the Great She-Bear) may be among the most archaic constellations, not least because the seven bright stars that mark the most recognizable part of the constellation (comprising the “big dipper”) are visible nearly year round from midnorthern latitudes. Even more remarkable is the observation that this collection of stars is thought to represent a bear figure in several different cultures. Notable among these are the native peoples of Siberia and Alaska. Owen Gingerich of Harvard University has proposed that this correspondence may date to the last glacial period, more than 12,000 years ago, when a natural land bridge across the Bering strait joined the two continents. The use of a bear image that wanders around the northern pole every day is consistent with the pervasiveness of the cave-bear cults of Paleolithic peoples.

There are other themes that might be extracted in the ancient constellations. Nearly all of the ancient constellations can be classified into three groups: images belonging to the air, anthropomorphic images that walk the earth and images associated with water. These three groups are nothing less than the symbols of the Upper (air), Middle (earth) and Lower (water) Worlds of ancient peoples. As it happens these groups correspond to three belts in the sky: Images associated with the Upper World of air or flight are concentrated near the north celestial pole, whereas the water-based images that correspond to the Lower World are located low on the southern sky. The Middle World, where human beings and animals walk the earth, lies between these two belts.

Ancient cuneiform texts reveal that the Sumerian-Akkadian sky of the second millennium B.C. was indeed divided into three pathways, those of the gods Enlil, Ea and Anu. Enlil was located near the zenith, Ea near the southern horizon and Anu between them. Who were these gods? Enlil was the deity for atmospheric phenomena and storms, Anu was the ultimate deity of beings in the Middle World and Ea was the deity of subterranean water.

How old is the notion that the sky holds these three strata? One possibility is that the strata are concentric upon the north celestial pole at the time they were conceived. When we plot this point on the northern sky we find that it is located between the constellations Cygnus and Lyra. Because of precession, the north celestial pole was last located here in about 14000 B.C. Might the three strata of the northern sky date to this ancient time period?

Future Research

The origins of the constellations should keep scholars occupied for some time. For now, allow me to offer some parting thoughts.

Consider the 42 constellations that were added to the sky since the “original” constellations of the classical Greeks. In general these newer constellations follow a rule: The younger constellations tend to be smaller than the older constellations. Might this rule be applied to the constellations of antiquity? A moment’s thought should reveal the logic: The first constellations that are described on an empty sphere should be larger than those figured on a partially filled sphere. If we test this idea on the zodiacal quartets, we do find that the average size of the constellations in the Gemini quartet is larger than those in the Taurus quartet, which in turn is larger than those in than the Aries quartet.

Why are the water constellations-Argo and Eridanus in particular-so much larger than the others? (The area of Argo was so unwieldy that 18th-century astronomers subdivided it into four constellations-Carina, Puppis, Pyxis and Vela-the ones we now recognize.) We do know that over the millennia the south celestial pole would have wandered in such a way as to reveal new stars above the southern horizon to observers in the midnorthern latitudes. Might these stars have been added to the existing constellations, in effect constituting a “zone of accumulation,” so that these constellations grew to their monstrous size? It should be noted that as new stars were added to the constellations in the the zone of accumulation, other stars would have disappeared in a “zone of erosion.”
Is it a coincidence that many of the constellations and asterisms that date to antiquity are often made of seven stars? We know that ancient peoples were fascinated with numerology, and that the number seven has a prominent place in Western mythology. Perhaps some of the earliest constellations were collections of the seven brightest stars in a region.

Unfortunately, we may never learn the answers to these questions. There is always the possibility, however, that some long-forgotten stone-age skywatcher made note of the star patterns his people recognized and recorded them on a cave wall that has yet to be discovered. It would have been the first star atlas.