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Posted by mkmk 1/20/2026

A 26,000-year astronomical monument hidden in plain sight (2019)(longnow.org)
565 points | 113 commentspage 3
staplung 1/21/2026|
The star map comes up at the end of Joan Didion's essay "At the Dam":

""" I walked across the marble star map that traces a sidereal revolution of the equinox and fixes forever, the Reclamation man had told me, for all time and for all people who can read the stars, the date the dam was dedicated. The star map was, he had said, for when we were all gone and the dam was left. I had not though much of it when he said it, but I thought of it then, with the wind whining and the sun dropping behind a mesa with the finality of a sunset in space. Of course that was the image I had seen always, seen it without quite realizing what I saw, a dynamo finally free of man, splendid at last in its absolute isolation, transmitting power and releasing water to a world where no one is.

"""

avhception 1/20/2026||
Haha, I clicked without reading the URL. Then I read the "01931" in the text, immediately looked at the URL and of course it was longnow.org. Brought a smile to my face.
antonvs 1/21/2026||
I find it a bit silly. When we refer to 70 CE or 500 CE we don’t add zeros in front.
sponnath 1/21/2026||
It's not silly when you consider what longnow stands for. They look at "now" on a 20,000 year scale so the extra zero is just emphasizing that 01931 is still the "long now".
antonvs 1/21/2026||
It’s so arbitrary. We have at least a few hundred million years before Earth is entirely uninhabitable. Why not use 000001931, then? Not ambitious enough, I guess.

Our written history already goes back over 6,000 years. We can actually understand what people back then wrote. We don’t need unbroken year numbering, or leading zeros, to understand that. The calendar has been reset and changed multiple times. It seems like a mis-focus on something that doesn’t really matter.

avhception 1/22/2026||
I don't see it as a serious attempt to create a better way to write down the year. To me, it's a whimsical attempt to give the reader a little pause to think about long time periods, which is what this project is all about. That makes me smile and remember that I'm just a small spec of dust, not to be taken too seriously in the grand scheme of things. I like it.
timc3 1/21/2026||
As a European it took me a few seconds to parse.

Nonsense formatting.

NetMageSCW 1/20/2026||
My wife has bought a few of these for significant dates as gifts:

https://thestarposter.com/

accrual 1/20/2026||
> Marking in the terrazzo floor of Monument Plaza showing the location of Vega, which will be our North Star in roughly 12,000 years. (Photo by Alexander Rose)

I wonder if some content creator 12K years from now will transport to Earth and stream the North Star from this position for likes/views. If that's even a thing then...

antonvs 1/21/2026|
> transport to Earth

They’ll almost certainly still be on Earth. Fundamental physics is unlikely to change in the next 12,000 years.

lalos 1/20/2026||
> Having this one fixed point in the sky is the foundation of all celestial navigation.

Only in the northern hemisphere.

kevinpet 1/21/2026|
Not even in the northern hemisphere. Celestial navigation is about shooting altitudes for known bright stars. At least three ideally five. This could include Polaris, but it doesn't need to. Source: watched some old training videos about celestial navigation after reading Fate is the Hunter a while back.
kraig911 1/20/2026||
I loved this. I wish I had the ability to do the same innocuous deep dive into a easter egg in code - but I fear it would never be discovered at this rate of which AI is generating similar stuff. But much like this article maybe there's a time and place.
tim333 1/21/2026||
I wonder if you can pin down other cycles in the sky to pinpoint how many years after the big bang? I guess the appearance of galaxies must change.
ProllyInfamous 1/20/2026||
During DEF CON XX, I got bored/overwhelmed (it was not my first year attending) — so I decided to rent a car and visit Hoover Dam (this was before the bypass bridge was completed). I drove through the desert 100mph+, in my own little HST jaunt, searching for nothing but concrete's high water mark.

The statues in OP's article are absolutely beautiful examples of Art Deco / 1930s Americana (my local post office was built then, too, and has eaglettes of similar [but smaller] design). I had no idea they were out there until stumbling upon them, and they definitely leave a lasting impression of our forefather's imposing presence. America, fuck yeah!

Wish I had then-known about this "clock," which is definitely hidden in plain sight. Wish we had similarly-lavish federal budgets, today. But worth visiting, both article, statues & dam.

hakkoru 1/21/2026|
Heh, a group of friends and I also visited the Hoover Dam while we were in Vegas for DEF CON one year. Was a really cool experience for sure.
ProllyInfamous 1/21/2026||
I actually went to get away from some friends, whom were presenting that year (they needed prep time — and I needed escape). Top 10 memories made by myself out at Hoover Dam, watching as the bypass got completed (that is another incredible feat of engineering).

Definitely a cool experience, and I'm glad I did. My last year attending DEF CON me and a Hadoop buddy (nobodies) just walked up onto a stage [during a terrible presentation] and started drinking whiskey with the ESL speaker (again: nobodies) — predicting we'd get banned from attending (but didn't — nobody cared... audience appreciated the break from hard-to-understandings).

ljsprague 1/20/2026|
>It is likely that at least major portions of the Hoover Dam will still be in place hundreds of thousands of years from now.

Kinda sus of this.

u1hcw9nx 1/21/2026|
It can be hard to recognize the heaps of dirt on the riverbanks. The internet claims the Hoover Dam could last 10,000 years, but I don't believe that for a second.

Dams are not permanent structures without maintenance. If they are holding back water or if water is flowing through them, they will eventually erode and their foundations will collapse.

Because the main structure lacks rebar , it will last longer than most modern structures, but it won't last nearly as long as 2,000-year-old Roman structures made with volcanic ash and lime because it uses Portland cement.

There is bigger and more immediate problem. Hoover Dam ends with siltation long before concrete erodes. The Colorado River carries massive amounts of sediment. Eventually, the lake behind the dam will fill with mud, turning the dam into a giant waterfall. Once water starts flowing over the top of a arch-gravity dam rather than through controlled pipes, scouring at the base will undermine the foundation.

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