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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 4
anentropic 1/21/2026|
Could plate tectonics conceivably throw off the alignment of this monument within the ~10ky timescales involved?
staplung 1/21/2026|
Not really. The axis of the earth's rotation is not affected by plate tectonics and the star map is recording where the earth's northern axis is pointing as precession slowly moves it around a circle. The star map could certainly move around or get broken up by plate tectonics over that timescale but it's not really aligned with anything in a meaningful way so that doesn't matter.

The stars themselves will move - relative to us - and eventually some of them will disappear but nothing much is expected on that front for much longer than 10ky timeframes.

flomo 1/20/2026||
Thanks for this, at one point I tried to google this monument and didn't find much.
hopelite 1/21/2026||
The civilization that created that must have been a wonderful place and probably was taught how to create such things by aliens.

Is sarcasm, but it may as well not be since that America is long dead and gone and has been replaced by an America that really needs to be renamed at this point.

gku 1/21/2026||
The 26,000-year cycle is also known as the Platonic Year.
IG_Semmelweiss 1/21/2026|
is that the time it would require to complete 1 revolution, shown specifically in figure 1 of the article ?

Also - wouldn't the north star(s) (polaris, deneb etc) also move, even if slightly, in that period of time as well ?

zehagray 1/21/2026||
The fact is; this kind of knowledge are mostly pursued by people called "lunatics" and this is taking science held back in fringe cases. But sometimes lunatics are right too
mockbuild 1/21/2026||
3.82

plein d’impressement: a series of cordialities

maximgeorge 1/20/2026||
[dead]
BLACKCRAB 1/21/2026||
[dead]
kazinator 1/20/2026||
[flagged]
ofalkaed 1/20/2026||
It is a convention of The Long Now Foundation to get people to think of time in terms of 10k years instead of a lifetime at best. It goes hand in hand with their 10k year clock.

https://en.wikipedia.org/wiki/Clock_of_the_Long_Now

zamadatix 1/20/2026|||
I think they are speaking to, not ignorant of, this.
antonvs 1/21/2026||
Yes. It’s an artistic choice, about as meaningful as the Hoover artist’s claim that, “There is an angle for doubt, for sorrow, for hate, for joy, for contemplation, and for devotion.” Both have a meaningful denotation in the mind of the creator, but don’t necessarily resonate with others.
kazinator 1/20/2026|||
> 10k year clock

a.k.a. cuckoo clock

krisoft 1/21/2026|||
> Just, stop.

Why do you mind what others do?

> A leading zero does not unambiguously say "there are no implied nonzero digits to the left of this zero".

Nor does it anywhere say that it means that or that it should mean that. To me the the leading zero in front of 1931 means “Do you think a thousand year is long? Think on a longer scale.” It is a vibe.

> Or is that the usual truncation of 101931, since most relevant dates are in this decamillennium?

The sentients of 101931 won’t be confused because they will know that 01931 refers to our time. Simply from all the context clues acrued. Such as the fact that the document was written in HTML (an archaic markup format rarely used past 8470 as any historicaly inclined sentient of that age would know) and found saved on an SD—card in the backpack of an astronaut who crash landed on the far side of the moon in 2457. Same as you don’t get confused about which milenia a roman public inscription unearthed in Pompei refers to.

AnimalMuppet 1/21/2026||
> The sentients of 101931 won’t be confused because they will know that 01931 refers to our time.

They may well be confused, because by then this silly "long now" stuff will be long since forgotten.

fc417fc802 1/21/2026||
Consider that every culture's predominant method of writing has undergone significant changes over a given millennia long period. I'm not about to confuse the date on a photograph of a wax tablet for a modern one.
AnimalMuppet 1/21/2026||
Right. But the long now format is a rarity, and doesn't look like it's ever going to become the norm. If someone from the far future stumbles upon it, they may well not know what millennium it comes from. It's just some date in an unknown format.
fc417fc802 1/21/2026||
That's like supposing that I (in the modern day) would stumble upon an ancient sumerian date formatted in a slightly unusual manner (for the time), lack the context to identify the approximate era, but somehow if it had been written without the extra character (or whatever) I would have been able to figure things out.

Either a future archeologist has sufficient context to localize the writing to within plus or minus 5k years or the situation was hopeless to begin with. In all likelihood the latin script itself will be sufficient. In the unlikely event that latin numerals remain in near continuous use for another 100k years the writing system alone would then prove insufficient but hopefully you see my point.

That said, it seems the latin alphabet has been in use for 2700 years and is used by approximately 70% of the global population at this point so I guess if any alphabet is going to survive that far into the future it's one of the top contenders. But even then the scripts and usage conventions have changed drastically since its advent. Do we really expect anyone to be employing anything that even vaguely resembles a present day font face that far into the future?

bravoetch 1/21/2026|||
Their stated aim is to encourage long term thinking. It appears they scored a bullseye with your response.
eddieh 1/20/2026|||
error: invalid digit '9' in octal constant
bregma 1/20/2026|||
I just look at it and think someone can't even count to 010 in octal.
GavinMcG 1/20/2026|||
Why do you imagine that =1931 wouldn’t be equally confusing in some future decamillenium? Arabic numerals have only been around for (charitably) 0.12 decamillenia. Sorry, =.12 decamillenia.
Aloisius 1/21/2026||
> Leading zeros don't do what you think they do

It's has been pretty normal for clocks with digital displays to include leading zeros for seconds, minutes, hours and/or days for about a century. Doing the same for years, while unusual, doesn't seem particularly confusing. And of course, there is precedent with things like ISO86011 - where 0400 is the year 400 CE.

I'm not sure why one would assume it was a truncation of 101931. That doesn't really make much sense. The first decamillennium digit started at 0, just like the first millennium digit started at 0. 101931 would be 99,905 years in the future.

> how people say 03 when they mean 2003

Making people think beyond that form of casual shorthand (even omitting the apostrophe which would indicate the omission!) is sort of the point? Never mind that 03 doesn't necessarily mean 2003.

kazinator 1/21/2026|||
If it is not reasonable that someone would assume 01931 is a truncation of some figure where some nonzero digits are implied, why is it reasonable that someone would assume that about 1931? (And that adding a 0 fixes it?)

How about this: 1931 is a complete decimal integer requiring no further adornment.

fc417fc802 1/21/2026||||
> I'm not sure why one would assume it was a truncation of 101931.

For the same reason one assumes that 03 refers to 2003 rather than 1903 (or 1803, or ...).

Of course, it's the surrounding historical context that resolves such confusion.

robocat 1/21/2026|||
IS086011 or 15O86O11 to be less precise.
calibas 1/20/2026|
Sounds like it's about the precession of the equinoxes and the new "Age of Aquarius".