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Do the buildings and markers at Chaco encode astronomy?

Asked 26 Oct 2026 by ·4 answers·0·0 following
Most likely: the Sun Dagger marks the solstices, equinoxes and lunar standstills, and great houses and shrines are aligned…Ahead on the evidence, not yet confirmed. It needs two reviews to be accepted.

Where it stands

Four answers have been proposed. The Fajada solar markings are deliberate but the site was a sun shrine, not a precise calendar, and the lunar… leads, with evidence 1 for, 1 against: partly supported by its tests. Three are still possible. Of the two narrower questions under it, none is answered yet.

Why it matters

Chaco is a type site for American archaeoastronomy. Whether the Sun Dagger and the building alignments track the sun and the 18.6-year lunar cycle decides how much astronomical knowledge can be credited to the builders⁠[1]⁠[2]⁠[3].

Answers 4

Evidence: 1 for, 1 against
Most likely
Evidence: 2 for, 1 against
Most likely
Evidence: 1 for
Still possible
None of these.
Not tested enough to call either way
Evidence: none yet
Still possible

History

  1. Sofaer et al. puts forward: the Sun Dagger marks the solstices, equinoxes and lunar standstills, and great houses and shrines are aligned…
  2. Sofaer et al.: light and shadow on the Fajada Butte spirals mark the solstices and equinoxes by the height of the midday sun.For: The Sun Dagger marks the solstices, equinoxes and lunar standstills, and great houses and shrines are aligned…
  3. Zeilik puts forward: the Fajada solar markings are deliberate but the site was a sun shrine, not a precise calendar, and the lunar…
  4. Zeilik: zeilik finds no ethnographic or functional support for lunar standstill use of the site.Against: The Sun Dagger marks the solstices, equinoxes and lunar standstills, and great houses and shrines are aligned…
  5. Zeilik: zeilik judged the marker unable to give accurate anticipatory solar dates in the Puebloan context.For: The Fajada solar markings are deliberate but the site was a sun shrine, not a precise calendar, and the lunar…
  6. Sofaer & Sinclair: sofaer and Sinclair published an appraisal disputing Zeilik's longer critique.Against: The Fajada solar markings are deliberate but the site was a sun shrine, not a precise calendar, and the lunar…
  7. Sofaer et al.: sofaer, Weiner and Stone report inter-site shrine alignments to the major lunar standstill.For: The Sun Dagger marks the solstices, equinoxes and lunar standstills, and great houses and shrines are aligned…
  8. Asked on this site
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