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Does the Sun Dagger also mark the 18.6-year lunar standstill cycle?

Asked 26 Oct 2026 by ·Part of Was the Fajada Butte spiral made and used as a solar calendar?·3 answers·0·0 following
Most likely: the lunar shadow positions are by-products of the slabs' shape; the site was not used to follow the…Ahead on the evidence, not yet confirmed. It needs two reviews to be accepted.

Where it stands

Three answers have been proposed. The lunar shadow positions are by-products of the slabs' shape; the site was not used to follow the… leads, with evidence 2 for: partly supported by its tests. Two are still possible.

Why it matters

If it does, the builders followed a cycle that takes 18.6 years to complete, which would put their astronomy well beyond sun-watching; the claim rests on slab shadows at moonrise and has no counterpart in Pueblo ethnography⁠[1]⁠[2].

Answers 3

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

History

  1. Sofaer et al. puts forward: at moonrise the eastern slab's shadow marks the moon's minor and major standstills on the large spiral, and…
  2. Sofaer et al.: at sunrise at declination +18.4°, standing in for the moon at its northern minor standstill, the eastern…For: At moonrise the eastern slab's shadow marks the moon's minor and major standstills on the large spiral, and…
  3. Zeilik puts forward: the lunar shadow positions are by-products of the slabs' shape; the site was not used to follow the…
  4. Zeilik: there is no ethnographic evidence that historic Pueblos attended to the lunar standstill cycle.Against: At moonrise the eastern slab's shadow marks the moon's minor and major standstills on the large spiral, and…
  5. Zeilik: historic Pueblo practice records sun-watching but not tracking of the lunar standstills.For: The lunar shadow positions are by-products of the slabs' shape; the site was not used to follow the…
  6. Sofaer et al.: in November 1987, at the major standstill, the project photographed the moonrise shadow of the eastern slab…For: At moonrise the eastern slab's shadow marks the moon's minor and major standstills on the large spiral, and…
  7. Schaefer & Stamm: one spiral designed to mark three or four separate dates is very unlikely; the extra dates are most likely…Against: At moonrise the eastern slab's shadow marks the moon's minor and major standstills on the large spiral, and…
  8. Schaefer & Stamm: the probability that a single spiral was designed to mark four dates is very small.For: The lunar shadow positions are by-products of the slabs' shape; the site was not used to follow the…
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