15.7: Dark Constellations

Science and Society: Dark Constellations

Cultures throughout the world have observed and used many phenomena of the night sky. This often included the grouping of stars into constellations or asterisms. Certain cultures also observed and identified features within the dark areas of the Milky Way where dust and gas block the light of the stars that they obscure. As with stellar constellations, dark constellations typically represent animals of significance within local traditions and cosmologies.

The attributed journal article for this section discusses seven case studies of cultures across various geographical regions that feature dark constellations in their knowledge and traditions: the Maya (Mesoamerica), Inca (South American Andes), Moqoit (Argentina), Tupi (Brasil), Aboriginal and Torres Strait Islanders (Australia), Bugis (Indonesia), Xhosa, Sotho, Zulu, and Tswana (southern Africa), and Polynesians (Pacific). Here, we'll focus on just one of these cultures--the Inca. We encourage you to peruse the rest of the attributed article for more details on the other six knowledge traditions.

Inca Astronomy and Dark Constellations

Inca cosmology viewed the Milky Way as a river flowing across the night sky in a very literal sense. They saw 'earthly' waters as being drawn into the heavens and then later returned to Earth after a celestial rejuvenation. The Earth was thought to float in a cosmic sea. When the celestial river's orientation was such that it dipped into the ocean, the water was drawn into the sky. Urton described the Milky Way as "… an integral part of the continuing recycling of water throughout the Quechua universe." The plane of the Milky Way is inclined between 26° and 30° with the axis of the Earth's rotation. This orientation is 26° toward the South Celestial Pole, and 30° toward the north.

The Milky Way at times will be viewed as rising in the southeast, passing through the zenith, and setting in the northwest. Twelve hours later the horizon positions have shifted, and the band of stars rises instead from the northeast, traveling again through the zenith, but now setting in the southwest. This 24-hour rotation cycle creates two zenith-intersecting inter-cardinal axes that divide the celestial sphere into four observable quarters.

The rising of the Milky Way figures prominently in Inca astronomy because of correlations with their inter-cardinal axes and the four points of solstice horizon events. At the time of the December solstice, when the Sun rises at an azimuth of 114° on the Cusco horizon, the evening position of the band of the Milky Way lies similarly to the southeast. During the June solstice sunrise at an azimuth of 64°, the Milky Way is situated in the northeast. The solstices are the only occasions when the Sun rises and travels with the Milky Way. Inca cosmology recognizes that the celestial river and the Sun rise together at the start of the dry season in June and the rainy season in December. This correlation explains the seasonal intensity of the Sun in Inca traditions, which feeds upon the powerful waters.

The Inca ordered their sky by this celestial quadri-partition. This contrasts with common use of the general path ecliptic travel as a reference marker. Urton (1981) argues that this gave the Incas a nearly 90° difference in their perspective of the heavens, and cosmological constructs were developed accordingly. He asserts that the primary axis for celestial references was east/west, rather than north/south, as was common in cultural systems in the Northern Hemisphere. The quadri-partition also appears to have influenced orientations on Earth. The pantheon of Inca dark constellations stretches nearly 150° across the Milky Way, shown in Figure \(\PageIndex{1}\).

Figure \(\PageIndex{1}\): The Incan Dark Constellations – right to left: (1) Machacuay, (2) Hanp'atu, (3) Yutu, (4) Yacana, (5) Uñallamacha, (6) Atoq, and (7) Yutu, constellations from Urton (1981). (CC BY 4.0; Jessica Gullberg via SciEngine).

Most are animals that figure prominently in Andean cosmology and traditions. Urton relates that the Spanish chronicler, Polo de Ondegardo, found the Incas to believe that "… the animal constellations were responsible for the procreation and augmentation of their animal counterparts on the earth." Serpents figure prominently in Inca cosmology and are the creatures representing Uchu Pacha, the underworld and lowest of the three worlds of Inca existence. Machacuay leads a dark celestial procession as the constellations move diurnally across the night sky. Van de Guchte says that the amaru (serpents) emerge from their underworld environs via rivers and are thought to be related to rainbows and to foretell of rain. Machacuay can be seen at the beginning of the rainy season. The serpent's dark figure is long, like a snake, and travels head before the tail across the sky. Hanp'atu (the toad) follows closely behind Machacuay. Toads were thought of as bad omens as they were created by the devil.

Hanp'atu is a much smaller dark section of the Milky Way to the left of the snake. Tinamou are birds indigenous to the Andes and are of very ancient lineage. Yutu, the Tinamou (the Coalsack) follows Hanpatu in the Milky Way and likewise is much smaller than Machacuay.

Yacana, the llama, figures prominently in many aspects of Inca traditions. This celestial figure was thought to animate the llamas on the Earth. The cosmic Yacana is much larger than Hanpatu or Yutu and dominates the Incas' dark section of the Milky Way. Yacana is situated between Centaurus and Scorpius, and the prominent stars Alpha and Beta Centauri are known as llamacñawin, the "… eyes of the llama."

Below Yacana is a smaller dark constellation called Uñallamacha. It is said to be a baby llama suckling its mother. Following Yacana and Uñallamacha in the sky from the left is the somewhat smaller constellation of Atoq, the fox. Atoq lies on the ecliptic between the constellations of Scorpius and Sagittarius. The Sun enters it during the December solstice. Urton explains that the Milky Way and Atoq catch up and rise with the summer solstice Sun in the southeast during the same period of time that terrestrial baby foxes typically are born, around 15‒23 December. Urton then lists a second constellation called Yutu. This additional tinamou follows Atoq and completes the celestial precession.

Unlike stellar constellations, dark constellations are unchanging features of our Milky Way and have been similarly viewed by humans since time immemorial. In case you find yourself curious to look for dark constellations, all you need is a dark sky and patience to let your eyes adjust. First try looking for the fuzzy, almost cloudlike features of the Milky Way itself. If you look long enough, you'll start to notice subtle shapes of bright and dark regions that make up these constellations, stretching across the entire sky.

References

• Bauer, B. S., & Dearborn, D. S. P. (1995). Astronomy and empire in the ancient Andes: The cultural origins of Inca sky watching. University of Texas Press.
• Gullberg, J. S. (2020). Dark constellations: Seeing the Milky Way through other eyes. Journal of Astronomical History and Heritage, 23(2), 337–358.
• Salomon, F., & Urioste, G. L. (1991). The Huarochiri manuscript: A testament of ancient and colonial Andean religion. University of Texas Press.
• Urton, G. (1981). At the crossroads of earth and sky: An Andean cosmology. University of Texas Press.
• Van de Guchte, M. J. D. (1990). Carving the world: Inca monumental sculpture and landscape [Doctoral dissertation, University of Illinois Urbana-Champaign]. University of Illinois Urbana-Champaign.