The precession circle is 144 arc degrees sin 23.5. In an 80 year lifespan precession would move the rotation pole about .44 arc degrees or the diameter of the full moon. Any long lived astronomical observatory in ancient times would have noticed this.
A 26,000-year astronomical monument hidden in plain sight (2019)
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Re: A 26,000-year astronomical monument hidden in plain sight (2019)
#52I have once created a pendant to my friends’ wedding following a similar idea. A silver disk engraved one one side with the position of the planets and major moons at the moment of the ceremony. Fun thing is that the Galilean moons orbit fast enough that you can even read the intended minute. https://www.instagram.com/reel/DIpFTPOIP60/
If you have a blog post with a few more technical details, it may be a nice submission for HN. (Do you have a few photos of the intermediate steps to share?) Some ideas/questions: How is it painted? Is it laser cut or by hand? Did you designed it? How did you do the calculations? Does Saturn have rings? Where is the cutoff? (No Neptune/Uranus/Fobos/Deimos/...) Have you tried to give a different size to each planet? P…
> If you have a blog post with a few more technical details, it may be a nice submission for HN.
Oh. That is very kind of you. I do have many more pictures and details. I will try to collect them together, and will publish it once it is done. But can’t promise that it will happen soon. So i will answer your questions here in the meantime.
> How is it painted?
The shapes are recessed and the recesses are filled with black nail polish. The excess nail polish was then scraped off from the flat upper surfaces leaving it only in the recesses.
It was very fiddly, and i don’t necessarily recommend this method for anyone. I have since learned how to enamel by melting glass powders onto the metal surface which is both easier and gives a better result. That is how i would do it today. (On my instagram the last reel i posted is showing that process, even though with a different design.)
> Is it laser cut or by hand?
A third and a fourth option. The planet side is machined on a cnc. First I etched the orbits with a v-bit, then cut the planets with a 0.8mm flat endmill, then cut the hole, and finally cut the outline. After that i etched the initials side chemically. As a resist i used self-adhesive vinyl which i cut with a plotter.
To be honest. I wouldn’t recommend this process either. It was super finicky, slow, and error prone. Today i would just etch and cut the metal with a fiber laser. In fact i bought a fiber laser because i got sick of the chemical etching and mechanical machining during this project. :)
> Did you designed it? How did you do the calculations?
I did design it! I’m very proud of it. The initials side was designed in inkscape while the planet side was generated with a python script. The script used the super handy skyfield python library for the calculations. (Which in turn uses the planetary ephemeris files published by the Jet Propulsion Laboratory.)
> Does Saturn have rings?
No ring of Saturn unfortunately. But it would be a cool idea!
> Where is the cutoff? (No Neptune/Uranus/Fobos/Deimos/...)
Unfortunately I don’t have a real good principled answer to this. Because of the machining I had a hard limit on the smallest details I could put on the metal. I did know that i wanted to put the Gallilean moons on there because their short periods meant that they provide good basis for the minutes and hours part of the date. I did know that i also wanted one of the gas giants to provide a “slow hand” to the clock to show the years, and to hopefully stretch out the period before the next time the solar system is in a similar position to very far into the future. And i wanted the inner planets and the Moon so people and future alien minds will recognise it as the solar system. Everything else was just futzing around with the script and finding a good compromise between not making it too large to wear and not making it too crowded either.
> Have you tried to give a different size to each planet?
I did, but it looked uneven and too haphazard to my eyes. Not saying it is impossible to make it neat with different planet sizes but I liked the diagram simplicity of keeping all the planets one size and the moons an other smaller size.
> I showed the video to my older daughter that is interested in astronomy and she likes it.
Oh thank you! That is lovely!
Re: A 26,000-year astronomical monument hidden in plain sight (2019)
#53> 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...
Re: A 26,000-year astronomical monument hidden in plain sight (2019)
#54Many Hindus celebrated Malay Sankranti a week ago. It was originally meant to coincide with winter solstice but because the Hindu dates are based on the position of the Sun against the background stars (as viewed from the Earth), precession over the last ~1700 years has driven it out of sync with the tropical calendar.
Re: A 26,000-year astronomical monument hidden in plain sight (2019)
#55I have once created a pendant to my friends’ wedding following a similar idea. A silver disk engraved one one side with the position of the planets and major moons at the moment of the ceremony. Fun thing is that the Galilean moons orbit fast enough that you can even read the intended minute. https://www.instagram.com/reel/DIpFTPOIP60/
That's so cool! Is there a calculator somewhere that can convert to/from dates and solar system position charts?
To calculate the orbital positions i used the skyfield python library. https://rhodesmill.org/skyfield/
They have a very handy example right on the landing page how one can calculate the positions and angles of a planet from a date.
The inverse was a bit trickier. But I also implemented a script which could “solve” a given picture backwards and give us a date. I believe i used binary search to narrow the date down first for the planet with the slowest period, and then refined the date around that timestamp using the position of the planet one faster. That way the estimate got more and more accurate and i didn’t need to brute force search a large time interval. (I applied the assumption that the date to be found is within half a saturn year from our current date, but if that assumption were incorrect it would have resulted in a solver failure during the refinement and thus detected.)
Re: A 26,000-year astronomical monument hidden in plain sight (2019)
#56Earlier quoted context omitted.
Wikipedia says similar [1]: > The concept of "religion" was formed in the 16th and 17th centuries. Sacred texts like the Bible, the Quran, and others did not have a word or even a concept of religion in the original languages and neither did the people or the cultures in which these sacred texts were written That said, GrowingSideways is mistaken. He is confusing the thing with the category of the thing. [1] https://…
> or even a concept of religion in the original languages IMO this and the sources it cites are wrong. A huge chunk of the Old Testament is about how God had to keep sending prophets to tell the Israelites to stop worshipping other deities. So while they may not have had a single word that was equivalent to 'religion,' they clearly possessed the same concept. They would just use the phrase "worshipping other gods."
Indeed.
There are many texts written in the Greek or Roman antiquity that compare the religions of various nations known to them, i.e. which compare their beliefs about their "gods" and their methods for worshiping or for praying.
There are entire books written about such subjects, e.g. "De natura deorum" ("The nature of gods") by Cicero.
The ancient people usually did not have a precise word with the definite meaning that "religion" has today, mainly because religious practices were intermingled with most of their daily activities, so there was not a very clear separation between religion and other things.
For example, a treatise on agriculture, besides explaining how to prepare the soil and how to select the seeds for sowing, would also give the text of a prayer that should address a certain god before or after the sowing, so that it will be successful. Similarly for any other activities where divine help was believed to be necessary.
Nevertheless, they had the concept of religion and they were able to distinguish things that were related to gods from unrelated things.
Re: A 26,000-year astronomical monument hidden in plain sight (2019)
#57Earlier quoted context omitted.
If you have a blog post with a few more technical details, it may be a nice submission for HN. (Do you have a few photos of the intermediate steps to share?) Some ideas/questions: How is it painted? Is it laser cut or by hand? Did you designed it? How did you do the calculations? Does Saturn have rings? Where is the cutoff? (No Neptune/Uranus/Fobos/Deimos/...) Have you tried to give a different size to each planet? P…
> If you have a blog post with a few more technical details, it may be a nice submission for HN. Oh. That is very kind of you. I do have many more pictures and details. I will try to collect them together, and will publish it once it is done. But can’t promise that it will happen soon. So i will answer your questions here in the meantime. > How is it painted? The shapes are recessed and the recesses are filled with b…
Out of curiosity were the positions (especially of the Galilean moons) actual simultaneous positions, or positions as seen from Earth, given the ~40 light-minutes distance between the Earth and Jupiter?
Re: A 26,000-year astronomical monument hidden in plain sight (2019)
#58>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.
Re: A 26,000-year astronomical monument hidden in plain sight (2019)
#59And to think we're all here building b2b SaaS
Re: A 26,000-year astronomical monument hidden in plain sight (2019)
#60But is the star map there? This article seems to imply that it got demolished in 2022: https://www.oskarjwhansen.org/news/save-the-star-map If so that is somewhat ironic. A message intended to communicate a date to thousands of years into the future got demolished a mere 86 years after its creation due to a drainage issue and a contract dispute.
I'd have to look at what it looked like before, but when I visited there earlier this month, I didn't see any restoration in progress and the star map was open. I didn't take a ton of photos in that area, and here are the only two of the monument I grabbed: