Topic
“Ancient Moonwatchers” by Dr. Erica Ellingson with the Department of Astrophysical and Planetary Sciences at the University of Colorado, Boulder.
Abstract
While the monthly and yearly cycles of the moon are familiar to most modern skywatchers, the longer and more subtle “lunar standstill” cycles are more difficult to track. Ancient skywatchers from around the world may have noted the shifting positions of the moon, but the evidence is sometimes unclear. In this talk, I’ll model how the precession of the Moon’s orbit causes small changes in the observed positions or moonrise and moonset over its 18.6 year period, and review astronomical and archaeological evidence from several sites from around the world that have been claimed as lunar standstill observatories. The most convincing is actually in SW Colorado, at Chimney Rock National Monument, and I’ll describe our activities during the current major lunar standstill season, including moonrise events in September 2025.
Picture of the Moon at Lunar Standstill at the Chimney Rock National Monument (https://www.chimneyrockco.org/) near the Four Corners area of Colorado.
Bio
Prof. Erica Ellingson,
Department of Astrophysical and Planetary Sciences,
University of Colorado Boulder
Dr. Ellingson is an astrophysicist who delights in using telescopes large and small, in space and at observatories around the world. Her work includes investigating galaxy clusters, the evolution of galaxies, black holes, and the mysterious cosmological forces of dark matter and dark energy.
Her research also includes historical and archaeo-astronomy and she is an editor with the international Journal of Skyscape Archaeology. She also teaches and produces educational programs at the Fiske Planetarium at the University of Colorado and is an astronomical consultant with the US National Park Service.
Location
The meeting will be at the First Evangelical Lutheran Church, 803 Third Avenue, Longmont, CO 80501.
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