# Oldest historic event

**URL:** <https://boards.straightdope.com/t/oldest-historic-event/390936>\
**Category:** Factual Questions\
**Created:** [February 5, 2007, 3:55pm UTC](https://boards.straightdope.com/t/oldest-historic-event/390936 "2007-02-05T15:55:16Z")\
**Posts on this page:** 3\
**Page:** 2

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**Author:** ![Cunctator](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Cunctator](https://boards.straightdope.com/u/Cunctator)\
**Post date:** [February 6, 2007, 5:52am UTC](https://boards.straightdope.com/t/oldest-historic-event/390936/21 "2007-02-06T05:52:48Z")

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[QUOTE=Chronos]  
**Mangosteen** , do you happen to remember when the “two dawns” was? I just tried searching for it, but the results are badly contaminated by fundies claiming it as verification of a Biblical miracle.  
[/QUOTE]  
[This eclipse site](http://sunearth.gsfc.nasa.gov/eclipse/SEhistory/SEhistory.html) gives the date of “China’s Double Dawn” eclipse as 20 April 899 BC. It’s the fourth one on the list of _Solar Eclipses of Historical Interest_.

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**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\
**Post date:** [February 7, 2007, 12:01am UTC](https://boards.straightdope.com/t/oldest-historic-event/390936/22 "2007-02-07T00:01:29Z")

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> [@](#):
>
> Nope, year is (theoretically) available. Sirius rising at dawn on the summer solstice (that’s what the “heliacal rising” bit references) occurs something like once every several hundred years. Obviously, Sirius rises daily, including on the day of the summer solstice. But there’s some sort of precessional thing, which I don’t understand well, that means that its rising just at dawn on that particular day occurs only once in a long interval, on the order of centuries. And I know that’s not a whole lot of help in clarifying matters – but it actually pinpoints a year during Menes/Narmer’s reign (noted above as ca. 3200 BC).

In principle, yes, but it would require extremely precise measurements, and I’m not sure I would trust the ancient Egyptian astronomers that far. I’m not even sure I would trust a modern astronomer with modern instruments and calculations that far: That’s down into the range where a difference in the heat shimmer towards the horizon could potentially throw the results off.

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**Author:** ![APB](https://avatars.discourse-cdn.com/v4/letter/a/8e8cbc/32.png) [@APB](https://boards.straightdope.com/u/APB)\
**Post date:** [February 7, 2007, 11:06am UTC](https://boards.straightdope.com/t/oldest-historic-event/390936/23 "2007-02-07T11:06:57Z")

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Although they are probably not quite the type of event that the OP was thinking about and are not exact to the day, the dates proposed for the felling of the trees used for ‘Seahenge’ were astonishingly precise.

> **[BBC News | SCI/TECH | Seahenge dated to spring 2050 BC](http://news.bbc.co.uk/1/hi/sci/tech/544947.stm)**
>
> Precise dating reveals that Seahenge, the remarkable ring of oak timbers recently uncovered on a UK beach, is 4,050 years old.

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