A 26,000-year astronomical monument hidden in plain sight (2019)

Encoding time in the sky

• Many found the Hoover Dam “star map” a compelling attempt to encode a specific date for far‑future readers using precession of the equinoxes and pole star shifts.
• Some referenced popular fringe authors as an entry point to this topic, with others dismissing them as pseudo‑scientific.

Ancient vs modern architecture and attention to the sky

• Commenters praised ancient and early‑20th‑century architecture for embedding astronomical and symbolic meaning, contrasting it with today’s construction optimized for cost and speed.
• Several noted that pre‑industrial peoples, lacking light pollution and modern media, naturally paid more attention to the night sky for calendars and survival, whereas contemporary society relies on apps.
• There was appreciation that some modern works (like this monument) still aim for long‑term, thoughtful design.

Astronomy, precession, and navigation

• Discussion covered precession, pole stars, and Milankovitch cycles, with links explaining how the celestial pole drifts and how current Polaris is a temporary north star.
• One correction: celestial navigation does not strictly depend on Polaris; it uses observations of multiple bright stars.
• People mused about using other celestial cycles to encode absolute time (e.g., planetary configurations, galaxy evolution).

The Long Now date format (“01931”)

• The “01931” notation sparked debate:
  • Supporters see it as an artistic device to nudge thinking toward 10,000‑year timescales, aligned with Long Now’s 10k‑year clock.
  • Critics call it arbitrary, confusing, or “nonsense formatting,” arguing leading zeros don’t solve ambiguity for future archaeologists.
  • Others counter that any future reader would rely on broader cultural/contextual clues, not just the digits.

Preservation and restoration of the star map

• A linked campaign claimed the terrazzo star map had been broken up during drainage work, upsetting readers who saw this as undermining its long‑term intent.
• Follow‑up links and first‑hand visitor reports indicate it has been or is being reconstructed; someone associated with the preservation site stated the restoration finished in late 2025.

How long will Hoover Dam last?

• The article’s suggestion that major parts may last hundreds of thousands of years drew skepticism.
• Critics point to siltation of the reservoir, erosion once water overtops the dam, and Portland cement’s limitations, arguing functional and structural failure will come far sooner.

Related long‑term/astronomical projects

• Commenters shared analogous ideas: star‑map posters, a wedding pendant encoding planetary and moon positions (with technical discussion of calculating and inverting such configurations), and commercial services that plot the sky for given dates.
• The Long Now Foundation itself got praise; some use “how would you build a 10k‑year clock?” as a way to provoke creative, long‑term thinking.