[HN Gopher] Part of the long-lost star catalogue of Hipparchus f...
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Part of the long-lost star catalogue of Hipparchus found in
medieval parchment
Author : JoeDaDude
Score : 112 points
Date : 2022-10-19 11:43 UTC (11 hours ago)
(HTM) web link (www.nature.com)
(TXT) w3m dump (www.nature.com)
| mordae wrote:
| Look for Connections by James Burke. Try YouTube.
| Karawebnetwork wrote:
| Paper: https://journals.sagepub.com/doi/10.1177/00218286221128289
| rkagerer wrote:
| Thanks! I still haven't found a photo of what I expected would
| look something like a star map with dots. Is the hidden text
| basically a list of coordinates and descriptions?
| burkaman wrote:
| Yeah I think "catalogue" is a better word and that's why the
| paper uses it, I don't think there is a visual "map".
| fsckboy wrote:
| I'm slightly annoyed by the description "first known map of night
| sky" because medieval is late, and there must be some cave
| paintings or carved stones with the sun and the moon at least.
| And "first known" must mean "earliest surviving", because
| wouldn't there have been a few maps in the Library at Alexandria?
| What about China?
|
| It's Hipparchus which dates the original, and doesn't make what
| it is less cool, but my brain thirsts for a little more
| clarity/context in the headline.
| dang wrote:
| Ok, we've put Hipparchus up there.
| ummonk wrote:
| It's not a map but a catalogue with coordinates.
| TheRealPomax wrote:
| One day, the Vatican vaults will be cracked open, and the amount
| of history we'll be able to piece together that we've been denied
| for centuries will make people shake their heads in disbelief.
| twblalock wrote:
| The Vatican archives are mostly open to researchers already.
| TheRealPomax wrote:
| Right: if they already know what they're looking for, because
| if they don't their application's just getting denied. No
| free roaming the archives. So that's a radically different
| situation compared to "here's what we have, everyone can
| access it."
| koyanisqatsi wrote:
| It's surprising that no one has applied ML techniques to
| historical documents like these. Scanning the documents to
| uncover some text that was overwritten would be a very useful
| technique for historical research. I'm pretty certain there are
| other hidden treasures like this one in some university archive.
| DizzyDoo wrote:
| > The phenomenon of precession -- in which Earth slowly wobbles
| on its axis by around one degree every 72 years -- means that the
| position of the fixed stars slowly shifts in the sky. The
| researchers were able to use this to check when the ancient
| astronomer must have made his observations, and found that the
| coordinates fit roughly 129 bc -- during the time when Hipparchus
| was working.
|
| That's amazing, using the discovered results themselves to step
| backwards and find out when the observations were made.
| antognini wrote:
| Somewhat related, but the Earth's rate of rotation changes
| somewhat randomly over the centuries due to tidal friction,
| tectonic motion, and climate change. These random perturbations
| add up, so over the course of a few thousand years, the
| rotation angle of the Earth can be uncertain by up to 70
| degrees or so.
|
| But because total solar eclipses occur at times that we can
| calculate and are only visible from specific locations on the
| Earth, geologists have been able to use ancient accounts of
| solar eclipses to constrain the long-term change in the Earth's
| rotation rate.
| pfortuny wrote:
| Just a question: 70 _degrees_ in just several thousand years?
| Is that a mistake?
| antognini wrote:
| Those were the numbers I saw when I was looking into this a
| few weeks back.
|
| If you think about it, a few millennia corresponds to
| ~1,000,000 days. So to know the rotation angle to within 10
| 30 degrees or so, you need to know the length of the day to
| better than one part in 10^7. But each year the length of
| the day changes by a few tenths of a millisecond, which is
| about 3 x 10^-8 of the length of a day. So you have to know
| the change in the length of the day reasonably well not
| only today, but at all times going back 2000 years.
|
| Those few tenths of a millisecond add up over thousands of
| years!
| pfortuny wrote:
| Ah, I see where your number comes from. However, those
| deviations should happen in both senses (adding and
| subtracting)? But thanks for the computations!
| [deleted]
| vikingerik wrote:
| He means 70 degrees of rotation within the daily cycle, so
| roughly 5 hours of rotation. (He's not talking about the
| rotational _axis_ orientation being off by 70 degrees.)
|
| 5 hours over thousands of years is known to be within the
| margin of unpredictable irregularities. Nowadays we
| compensate for these irregularities by altering our
| timekeeping by way of leap seconds.
| pfortuny wrote:
| I got this idea late, thanks. My mistake. That makes
| sense.
| doctoboggan wrote:
| The precession of the earths axis is around 26,000 years for 1
| cycle. What's incredible is that the ancient babylonians were
| able to detect and measure this at the time.
| mikeyouse wrote:
| It's a slightly different take on it but there's a popular
| TikTok account (and I assume a related community) where people
| find old globes and then try to pinpoint when they were printed
| based on the labeling of disputed territories, renamed
| countries, redrawn lines etc. Its fascinating how specific they
| can get.
|
| https://www.tiktok.com/@jakie62/video/7140007175476235562
| JoshTriplett wrote:
| https://xkcd.com/1688/
| mikeyouse wrote:
| Of course there's an XKCD for that. Amazing, thanks for
| sharing.
| HeyLaughingBoy wrote:
| I remember back in the early 90's seeing for the first time a
| post-WW2 map that just said "Germany." Not East Germany and
| West Germany, but just Germany. Stood and stared at it for
| while with a weird mix of emotions.
| jamesmaniscalco wrote:
| This sounds like a kind of historical GeoGuessr.
| dylan604 wrote:
| Back in the 90s, there was a documentary* on the pyramids at
| Giza that took the wobble into consideration. There are holes
| that in modern times do not appear to have much significance,
| but winding the clock back && adjusting for the wobble aligns
| said holes with significant stars. There's a foggy memory that
| this theory might have been debunked, but it was the first time
| I had heard of the wobble being used in such a manner.
|
| *I have no recollection of a title. Just recall watching it on
| VHS. One of those nights at Blockbuster when all of the "good"
| movies were unavailable so went to find something else from the
| middle of the floor
| ljf wrote:
| Not the documentary but:
|
| https://en.wikipedia.org/wiki/Star_shaft
|
| And related:
| https://en.wikipedia.org/wiki/Orion_correlation_theory
| dylan604 wrote:
| Yes, I should have remembered it being Orion. Just seeing
| your link reminded me how their theory said the pyramids
| were positioned along the Nile similar to how Orion is
| positioned to the Milky Way. Now I'm going to read the wiki
| link to see how my memory holds up.
|
| Edit: yup yup. The wiki link gave the name of the
| documentary, and of course it's on youtube:
| https://www.youtube.com/watch?v=cfgRF1e66_8
| schrijver wrote:
| My history teacher made us watch this in high school when
| it just came out! She was very into it, at the point
| where the scholar who works for the Egyptian state starts
| voicing his criticisms she told us this was the response
| of a man afraid to loose his power :)
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(page generated 2022-10-19 23:00 UTC)