The duration of night and day follow a cyclic pattern based on our location with respect to the sun. Twice a year the timespan of light and dark almost exactly match up at all latitudes. This occurrence is called an equinox, derived from the Latin words for “equal night.” Here in the Northern Hemisphere we transitioned into the fall season on September 22nd during the autumnal equinox, when the Sun was exactly above the Equator.
The seasonal transitions that accompany the Earths elliptical orbit of the sun have been extremely influential on human culture for agricultural, spiritual, nomadic and other purposes. Ancient time-keeping systems were created by many peoples to predict equinoxes and solstices. Throughout the world and especially the southwest states these ‘clocks’ still exist and are more accurate than our modern wristwatch.
"File:Ancient Roman time keeping hora vigilia duration.gif" by Darekk2 is licensed under CC BY-SA 4.0
Many ancient carvings in stone known as petroglyphs like the ones studied at Wupatki National Monument, which the Hopi call itaakuku (“our footprints”) act as solar markers (Hedquist). They were created from the ancestral peoples of “modern day pueblo tribes such as the Hopi in northeastern Arizona and those that reside in New Mexico including the Acoma, Laguna, Zuni, and the Pueblo people living along the Rio Grande River” (Balenquah). By interacting with shadows differently during celestial events such as an equinox, the footprints can be interpreted as a calendar and a way for people to connect with their ancestors.
The study of cultural astronomy is an anthropological perspective on different cultural understandings, both ancient and modern, of celestial objects. During this years Flagstaff Festival of Science, Bryan Bates shares how Hopi ancestors developed a solar calendar and how it ties to their culture. Check out the video here.
Balenquah, Lyle. “Beyond Stone and Mortar: A Hopi Perspective on the Preservation of Ruins (and Culture).” Heritage & Society, vol. 1, no. 2, 2008, pp. 145–162., doi:10.1179/hso.2008.1.2.145.
Hedquist, Saul L., et al. “Mapping the Hopi Landscape for Cultural Preservation.” Geospatial Research, 2016, pp. 1066–1085., doi:10.4018/978-1-4666-9845-1.ch050.