By 1200 B.C.E., about five thousand people lived at Poverty Point on the lower Mississippi River. The town featured earthworks consisting of two large hills and six concentric dams, the outermost of which spanned more than half a mile in diameter. During the spring and autumn equinoxes, a person standing on the larger mound could watch the sun rise directly over the village center. As elsewhere in the Americas, solar observations were the basis for religious beliefs and a calendar.
–What is an Equinox | Video by National Geographic
What happens when it comes to spring or autumn "equinox"?
