[HN Gopher] When will the eclipse happen? A multimillennium tale...
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When will the eclipse happen? A multimillennium tale of computation
Author : nsoonhui
Score : 91 points
Date : 2024-03-30 06:01 UTC (16 hours ago)
(HTM) web link (writings.stephenwolfram.com)
(TXT) w3m dump (writings.stephenwolfram.com)
| stblack wrote:
| Mathematica's SolarEclipse[] function, introduced in v10 and
| seriously updated in v14, is a gem.
|
| https://reference.wolfram.com/language/ref/SolarEclipse
| m463 wrote:
| I wonder if he wrote it.
| 7thaccount wrote:
| I'm a big fan of Mathematica even though all commercial software
| irritates me on some level (transparency, cost, and licensing
| annoyance).
|
| As a result I follow Stephen's blog and sometimes they come off
| as a little self serving and grandiose, but this one was terrific
| to me as a non physicist in better learning the history and
| challenges of all of this. It's hard to understand sometimes that
| celestial mechanics is simply not a "solved" problem these days.
| javajosh wrote:
| What a truly lovely piece of work. I'm so glad that Wolfram
| adores math and science, and history, so much and has the tools
| to craft an excellent precis like this. It's always good to go to
| original sources, and connect with the deep past of learning to
| which we are the grateful inheritors. Predicting eclipses, and
| the details of how it was and is done, is probably considered by
| many to be pointless, boring, or even harmful (stealing
| intelligent attention away from more pressing problems, or any
| number of other reasons). But I think it's beautiful to retell
| these stories and appreciate them and the minds behind them.
| There is something so entirely wholesome about a learned man
| appreciating the work of his forebears. Wonderful.
| BoiledCabbage wrote:
| Agreed, it was a really nice read. Even simply in the role of
| an educator I've taken a liking to his blog posts. There is a
| certain combination of both breadth and depth that I've not
| found anywhere else. His overview of how LLMs work from last
| year was on of the first really good pieces describing them
| truly from first principles. And still shapes how I describe
| their workings to people outside of tech.
| huppeldepup wrote:
| FYI, this site shows an nice plotted overview per region and
| period of time:
|
| https://www.timeanddate.com/eclipse/list.html?region=europe
| wrycoder wrote:
| I have the Classic Wolfram app on iOS. I asked it, "When is the
| next partial Solar eclipse in New Hampshire?" It missed the 2024
| one and started giving details about a 2026 eclipse in Spain.
| sockbot wrote:
| Is there a closed form solution for this or is it an example of
| the three body problem?
| zamadatix wrote:
| See the "The Three-Body Problem" and several following
| sections. The fixed geometric approximations earlier in the
| article can have a closed form though.
| hinkley wrote:
| I can't believe that when the last time this eclipse happened my
| friends had to twist my arm into pausing whatever important thing
| I was doing to go outside and see it because this wouldn't happen
| again for thirty years, in 2024. I would be SO OLD then and
| probably not living there anyway so seize the day!
|
| Fuuuuuuck.
| Archelaos wrote:
| The author does not give sufficient credit for a particular
| difficulty in calculating the location of a solar eclipse. He
| mentions in pathing that "the rotation of the Earth is gradually
| slowing down" and that "exactly when a new leap second will be
| needed is unpredictable". More precisely, he should have said
| that the Earth's rotation has a tendency to slow down - in
| contrast to today, it accelerated somewhat in the last third of
| the 19th century, for example. But more significant in this
| context, however, is the aspect that the estimation of the degree
| of change for a given period of time becomes quickly more and
| more inaccurate when we go forward or backward in time. In the
| case of ancient eclipses we cannot calculate their exact location
| from a prior knowledge of the Earth's rotational speed. It is the
| other way round: since we have historical reports from a
| particular region about an eclipse we can deduce the change in
| the Earth's rotational speed between now and then.
|
| For more information about the change of Earth's rotational speed
| see the Wikipedia article on "DT (timekeeping)":
| https://en.wikipedia.org/wiki/%CE%94T_(timekeeping)
| quinncom wrote:
| Wolfram's Precision Eclipse website gives the wrong time for the
| eclipse at my location (23.7188, -105.6706).
|
| It says, "Total Eclipse begins at 1:09:31 PM CST":
| https://precisioneclipse.com/Results/46/b7/46b7ed589f764aec....
|
| In fact, C2 will be at 18:09 UT, which is 12:09 CST (-0600):
| https://eclipsewise.com/solar/SEgmapx/2001-2100/SE2024Apr08T...
|
| Can anyone confirm the correct time? I wonder if
| precisioneclipse.com isn't considering that Mexico abolished
| daylight savings since Oct 2022.
| bombcar wrote:
| That's almost certainly it - I don't know they abolished it
| entirely; it used to be offset a few weeks.
| heikkilevanto wrote:
| The Anticythera Mechanism was able to predict eclipses some 2000
| years ago. Anyone know if its predictions would still be useful?
| dmd wrote:
| That is discussed extensively in the linked article.
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