[from sign beside this lovely pavement design outside the National Museum of the American Indian, Washington, DC]
“Lunar Calendars”
“The circles and moon phases marked on the pavement refer to a phenomenon known as lunar standstills. Lunar standstills occur every 18.6 years when the moon reaches a northern extreme at summer solstice and a southern extreme at winter solstice. This also occurs with the sun, twice a year around each solstice date. When the sun and moon reach these points, they appear to stand still in the sky. These moon phases represent circular markings found in New Mexico’s Chaco Canyon and honor the ancient cultures that lived there and observed lunar cycles.”

October 12, 2016

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