Possible Prehistory of Constellations
When were the first constellations recorded? In 1997, Michael Rappenglück suggested that a painting found in a cave at Lascaux in Southern France might show at least parts of a star map. This painting dates back to roughly 15,300 BCE and shows a half-bull figure with black dots on and to the left and right of its head. Rappenglück speculates this image might show the constellation Taurus with the Pleiades and Hyades star clusters. Was this the first-ever depiction of a star pattern made over seventeen millennia ago?
It may look promising, but as there are no written descriptions from the Stone Age, it is hard to ultimately prove (or disprove) this hypothesis. In contrast, we know that our constellation of Taurus, the Bull, with the Hyades and Pleiades star clusters, went into the Greek uranology from a Babylonian and earlier Sumerian tradition. The halved depiction of the Bull in the sky is discussed in the Sumerian epic Gilgamesh, and the Greek name of the “Seven Sisters” for the Pleiades originates from a Greek misreading of the Babylonian MUL.APIN catalogue in combination with an own Greek weather rule for the sailing season (Greek: sailing = pleio). It is known that Akkadian scholars read Sumerian and that the Greeks studied the astronomy written in cuneiform. Therefore, the transformation of names and images from the 2nd millennium BCE onwards is understood. There is, however, insufficient evidence from before this period to make any strong claims about the evolution of constellations and star names.
A painting in a cave at Lascaux, in Southern France. Some researchers speculate that this is the first recorded image of a constellation (Rappenglück, 1997). Image credit: Ministère de la Culture/Centre National de la Préhistoire/Norbert Aujoulat.
The History of Star Catalogues
Throughout human history and across many different cultures, names and mythical stories have been attributed to the star patterns in the night sky, thus producing what we know as constellations.
Written scripts were invented in the 4th or 3rd millennium BCE at various places in Eurasia: the Mediterranean, North Africa, the Near East, and China. Eurasian astronomical texts (that are not mythological in origin) have survived from the beginning or middle of the 2nd millennium BCE. The oldest astronomical compendium known is the Babylonian MUL.APIN, dating between 1450 BCE and 1000 BCE. This includes a catalogue of asterisms, single stars, and constellations. MUL.APIN was used and copied for roughly a millennium until cuneiform died out in about the 2nd century CE. Even when Greek scholars started to compile a new star catalogue, the first with a complete set of coordinates for hundreds of stars, the MUL.APIN was still in circulation.
More than half of the 88 IAU-recognized constellations are attributed to the Ancient Greeks (last compiled by the mathematician and astronomer Claudius Ptolemy), who consolidated earlier works by the Ancient Babylonians, Egyptians and Assyrians (Hoffmann, 2021; Hoffmann and Wolfschmidt, 2022). Forty-eight of our 88 constellations were recorded in the seventh and eighth books of Ptolemy’s Almagest. However, the constellations’ exact origins remain uncertain: a “new Greekness” was invented during Alexander the Great’s empire in the 4th century BCE, which consisted of many individual cultures and aimed to combine them. In this way, the Babylonian zodiac as well as the Syriac, Egyptian, and likely many other originally indigenous constellations were incorporated under “the Greek” uranography and uranology.
Ptolemy summarised and based his studies on the work of earlier Greek scholars like Eudoxus of Cnidus, Aristotle, Hipparchus of Nicaea, and even the original Babylonian compendia. Note that Ptolemy lived during the Roman Empire (under the reign of Hadrian, whose young lover Antinous was deified and imagined in the constellation of Aquila), wrote in Greek (the lingua franca of science), used Egyptian month names, and counted the years after a Babylonian king. This shows the highly multicultural nature of his work, the Almagest, and suggests that the constellations he used are a similar mixture.
The Almagest star catalogue provides the positions of stars in ecliptic coordinates (longitude and latitude on the celestial sphere) because Ptolemy realised that precession shifts only the longitude systematically and does not change latitudes at all. With a known precession constant (given in the catalogue and iteratively made more accurate in subsequent centuries), star positions from the Almagest could still be used a few centuries later with adjustments from simple mental arithmetic. The error in the coordinates due to an inaccurate precession constant became significant only after a millennium, while the visual appearance of the constellations never changed. Images separated by a millennium show how the Almagest remained relevant for many centuries.Arabic, Jewish and Christian astronomers used the Almagest star catalogue. In two big waves of translations of Greek scientific books into Arabic, scholars in Damascus and Baghdad preserved much of the ancient heritage for later availability. In the 8th century CE, the Abbasid caliphs in even founded the Bayt al-Ḥikmah (House of Wisdom) in Baghdad for this gigantic enterprise and employed scholars of all religious and cultural background in order to obtain the best possible results. In this Golden Islamic Age, Arab astronomers not only commented on the historical star catalogue but also improved it – as well as many further aspects of astronomy, e.g. the concepts for explanations of the Milky Way (al-Haytham), the instruments for measuring positions of stars (al-Farghānī) and planet theories (at-Tusi). The Persian astronomer Abd al-Rahman al-Sufi in 964 CE published his Book of Fixed Stars with some of the brightness estimates (magnitudes) corrected with regard to the Almagest (Hafez 2010). as-Sufi’s book is also the only modern source for indigenous Arabic star names because in some cases, he added these to Ptolemy’s descriptions of the positions of the fixed stars within the Greek constellations.
In the 15th century, the Timurid sultan Ulugh Beg built an exceptionally large observatory in Samarkand and improved 27 of the positions of stars in the Almagest (Verbunt and van Gent 2012). Between the 16th and 17th centuries CE, European astronomers started to systematically re-observe star positions and added stars farther south during their exploratory voyages. With more stars known, celestial cartographers added new constellations to the 48 previously described in Ptolemy’s Almagest (Ridpath, 1988; Hoffmann, 2021). The Dutch navigators and cartographers, Frederick de Houtman and Pieter Dirksz Keyser, acted on behalf of the Flemish mapmaker, Petrus Plancius. They were commissioned to precisely measure stars in the southern sky during their first East India expedition (1594-1596), which took them around South Africa to Madagascar and Indonesia. They expanded the classical constellations Argo and Eridanus further south as they used the (Southern) Cross and the chain of stars south of Eridanus to find the south pole of the sky. Later, they cut the southernmost part of the longer Eridanus and named it Hydrus (Hyi). To avoid confusion with the asterism of the False Cross, they (1) attached the stars of this asterism to Argo, thereby enlarging the ship, and (2) invented the Fly (Mus) and the Southern Triangle (TrA) next to the actual (Southern) Cross.
They additionally invented new constellations and named them after the spectacular nature they observed, for example Flying Fish (Volans) hunted by Dolphinfish (Dorado). After these first additions, European astronomers and cartographers competed to invent new constellations. Some gaps between constellations of the northern hemisphere were closed with the invented constellations of the Polish-born German couple of astronomers Jan and Elżbieta Heweliusz and some English monarchists in the 17th century. In the 18th century, the French astronomer Nicolas-Louis de Lacaille filled in gaps in the south. Figure 2 below outlines the origins of these Western constellations.
Blue: Greek — Cet, Peg, Cas, And, Cep, Cyg, Her, Ser, Dra, UMa, UMi, Crt, Cen, CrA, Ara, Arg, CMa, CMi, Aur, Eri and Tri. Com was invented in Greek-controlled Egypt.
Tan: Babylonian — Aqr, Cap, Sgr, Sco, Aql, Oph, Lib, Vir, Boo, CrB, Hya, Crv, Leo, Cnc, Gem, Ori, Tau, Per, and Ari.
While the other Babylonian constellations were simply renamed (their images basically left intact), Psc is a product of transformation from the original Babylonian image called Tails of the Giant Swallow to a Swallow-Fish and then, in combination with Syriac and possibly Egyptian images, to the Greek version we know today.
Light Green: de Houtman and Keyser (1596) — Hyi, TrA, Mus, Pav, Phe, Tuc, Aps,Gru, Ind, Vol, Dor, and Cha. They additionally extended the old constellations Arg and Eri.
Pink: de Lacaille (1756) — Ant, Tel, Mic, Oct, For, Hor, Pyx, Men, Scl, Pic, Cae, Nor, Ret, and Cir, named after instruments and professions. These filled the gaps between classical constellations in the Southern Hemisphere. Because the newly enlarged constellation of Argo, then, counted so many stars that their list stretched over many pages of Lacaille’s catalogue, he introduced subheaders and this way, divided Argo into the three constellations Vel, Pup, and Car.
Dark Red: Heweliusz (1687) — Sex, Sct, LMi, Lyn, Lac, and Vul. They also were the first to depict CVn as dogs, although the area had been considered as a separate constellation (Cor Caroli) earlier by English monarchists.
Dark Green: Various (ca. 1660) — CVn. A group of English monarchists named the bright star Cor Caroli after the beheaded King Charles I in the course of the inauguration of his son, Charles II. Subsequently, the constellation around this star was developed by European astronomers in reference to this story. The Polish-German couple of astronomers J.+E. Hevelius named it “The Hunting Dogs”.
Yellow: Christian (16th and 17th century CE) — Sct, Cru, Col, and Mon. In the case of Crux (Cru), these stars originally belonged to the Greek constellation Centaur but were separated as a navigational tool during the 16th century. It is first depicted as a constellation in the Uranometria and the works of Plancius.
Brown: Unknown — Cam is probably an invention of Plancius, but the story is unknown.
The above outlines the history of the 88 constellations recognized by the IAU, which are based upon the Almagest tradition — for a more detailed account, see the IAU Theme The Constellations — but countless cultures from across the world created their own mappings and understandings of the night sky.
Contemporary Development
By the 19th century over a hundred constellations could be found on various star charts since there was nothing to stop astronomers inventing new figures between the existing ones, which they often did to flatter a patron or monarch. In the 19th century, there were several changes in the scientific method and research focus. Many variable stars were discovered, stellar transients were investigated and astrophysics with photoelectric measurements of brightnesses and even spectra of stars were developed. With the high number of investigated stars, new nomenclatures were developed, many of them relying on the constellation names. Therefore, one of the IAU’s first tasks after its formation was to define an internationally agreed set of constellations. At its first General Assembly held in Rome in 1922 the IAU’s Commission on Notations and Units agreed on a list of 88 constellations covering the entire sky, with three-letter abbreviations of their Latin names. These are the 88 constellations that are still recognized today, as described in more detail below.
But these constellations still lacked officially defined boundaries, and this was the next task to be tackled. At the second IAU General Assembly held in Cambridge, England, in 1925, Eugène Delporte of the Royal Observatory in Brussels presented proposals for a clearly defined system of constellation boundaries drawn along lines of right ascension and declination, the celestial equivalents of longitude and latitude on Earth. The IAU took up the suggestion and appointed Delporte to prepare official boundaries with the specific requirement that all known variable-brightness stars should remain within the constellation to which they had already been assigned. This resulted in some awkward-looking outlines.
Delporte’s new boundaries were approved by the IAU at its General Assembly at Leiden in 1928, and the results were published in 1930 in Délimitation Scientifique des Constellations along with an accompanying Atlas Céleste. So constellations, which started out as imaginary patterns of stars, became scientifically defined areas of sky. Nowadays when astronomers say something is “in” a given constellation they mean it is simply within those defined boundaries, not that it is part of any star pattern.
More Information
- UNESCO Portal to the Heritage of Astronomy: The Astronomical Rock Panels in the Lascaux Cave, France
- Arabic Star Catalog, courtesy of Danielle Adams
- Animations showing the transformation of constellations over time, courtesy of Susanne M. Hoffmann
Acknowledgements
This contribution was developed by Susanne M Hoffmann, Kelly Blumenthal and Ian Ridpath.
References
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