The local archaeologist? Incredible

You're that guy who lives on the northeast island of the Chrono Trigger map, aren't you?

We also have these in Germany, in the region where I live it which is North Rhein Westfalis they are quite a common thing actually. Strongly recomment people check it out if they pass by here some time

> as are they everywhere else, presumably!

They aren't "all over the place" in the US, and I certainly don't have a local archaeologist that I can just call up.

FWIW: The Northeastern US is quite recent with human presence. It wasn't settled until after the last ice age. Pretty much anything old is celebrated because there is so little of anything old.

That's.. neat. I guess lots more people show up for summer solstice though? Or are they occupied with the mainstream-pagan Midsummer celebrations then?

https://www.bbc.co.uk/news/live/c4g4exnj2p5t?page=2 8,500 turned up at Stonehenge in the UK.

Depends on where in India you are from. Winter solstice times with chillai kalan [0] which is treated as a headache. Everything basically shuts down in the Western Himalayan regions of India around this time - from Ladakh to Kashmir to Upper Himachal and Uttarakhand [1], though it has gotten much drier/warmer compared to the stories my parents or grandparents told.

[0] - https://www.tribuneindia.com/news/j-k/snow-rain-in-higher-re...

[1] - https://www.tribuneindia.com/news/himachal/snow-likely-on-de...

Ha, amazing, I build the same 24 hour clock with night time for daily planning.

You can use an js SVG animation to have it run in real time: https://tomchen.github.io/animated-svg-clock/clock.svg

I have no idea why we stuck with the 12 hour clocks once we stopped using sundials and variable hours: https://en.wikipedia.org/wiki/Unequal_hours

For a modern equivalent, the first thing that came to my mind was Manhattanhenge:

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

Doesn't really work on my setup (0). I am curious if it does more than the PhotoPills app, quite a useful thing for city scapes photography.

0. https://drive.google.com/file/d/1FB3Ofl4mUvOO4gGqARro9cO_kjJ...

/edit: Looks like noscript blocks the p5 thing.

With your app, it seems daylight today in Chicago is the same length as yesterday's solstice, although it starts and ends 30 seconds later.

today - 07:18:59 → 16:24:29 = 9:5:30. yesterday - 7:18:23 → 16:23:53 = 9:5:30

and yes, the maths fails when you are super super high north or south

1. Go out every morning to work in your field. 2. When the Sun rises, make a note on the same fixed piece of wood, e.g., a fence. 3. Observe the leftmost and rightmost positions, these are your solstices. 4 You can now use your fence to identify and predict solstices.

Honestly I bet you would have at least a reasonable intuition about it if you were among them. It's pretty remarkable how much our distractions and 'being indoors' all the time dulls our senses to nature.

I started doing astrophotography about three years ago. I'd always been interested in 'space' but never really spent hours upon hours out at night over the course of months actually just studying the night sky. I remember wondering as a kid how people even thought about planets or came up with these wild stories with the constellations...to me it just kind of looked like a bright field of randomly twinkling lights.

Well, when you're out every night from 10pm to 2am looking up, it all just kind of comes alive. You see everything. The motion of the planets, the elliptic upon which they travel, the gradual shift of the entire field as the seasons change, the undulations of the moon and it's varied trajectory across the sky. The shifting of the sun's set and rise and the ebb and flow of day vs night. Everything. Your mind just starts to harmonize with the rhythm of it all. It's pretty wonderful.

It seems unintuitive today because people living in cities and towns don’t usually see sunrises and sunsets from where they live. If you had a way to easily reference the sunrise and sunset points against known horizon, it’d be very easy to tell.

For very ancient people, it's the longest/shortest day.

After you notice that, if you want more precision, it's the day the Sun rises and sets most on the North/South. It's also the day things cast the largest shadow at noon. You will need some special device to get very precise on the sun raising position (like a pair of stones or something with a hole), and you won't be able to get precision on the shadow thing.

For more modern people, starting about only half a dozen millennia ago, it's the hour the Sun stops moving North/South within the stars and starts moving the other way around. You will need to look at it and take notes many times, and average things out to get any precision. Even more because you can't see the Sun and the stars at the same time, so you have to model them.

Pre technology, the sky was very central to life. Sunlight, rain and snow dictated much of your life (and death), and you probably considered the sun, moon and five planets as gods.

You and I personally may not have kept track, but our local religious leader did, and maybe the even staged a ceremony at the winter solstice to ask the sun to make the days longer.

Probably easier to measure the location of sunsets and sunrises rather than the time?

Edit: Obviously somewhere like here in Scotland observing the sunrise is easier said than done - particularly at this time of year!

Wikipedia says it's indeed not a trivial thing

https://en.wikipedia.org/wiki/Solstice#Solstice_determinatio...

> How did ancient cultures know when the solstice was

Solstice is a small thing they figured long ago, there are things they managed that are much more complex than that. In India there are whole temples dedicated to astronomy and built to align with different celestial geometries.

They could reason about the Pythagorean theorem in 2000 BC. It's not a surprise they could figure out when the sun set in 2800 BC.

They didn't.

They didn't like go out on Dec 21st, and look where the sun was and mark it. They didn't even have calendars like that. They watched the sun every day, and waited until it stopped being lower in the sky at it's highest point in the day (or whatever other sign of the solstice they wanted to use), and marked that angle and built whatever viewport they wanted (a door, tunnel, etc).

Then they could just go wherever they built the thing that pointed at that point in the sky, and go, oh, okay, the solstice is soon, or just happened, or whatever and plan accordingly.

It actually wasn't really accurate to the day, anyway. There are a few days on either side of the solstice where the effect is basically the same for the viewer.

Something to keep in mind is that this isn't only useful for determining the exact date of the winter solstice, which they may not have even cared that much about. You can see roughly where you are in the year on either side of the solstice by looking at how far out of alignment the sun is on a given day. So it could be useful throughout the fall and even well into the winter for gauging the passing of time. People didn't need to plan day by day or even week by week, but they did need to do things in roughly the right part of the year.

People act like this is some unexplainable advanced technology, and anybody can just do this with a stick and some rocks.

To tell it accurately of course takes work.

However if you live in the open, or have daily access to the open sky, after a while you are bound to notice.

We are so used to having a ceiling above us, so used to constructions blocking our view of the sky that this seems a feat.

I was the same till I got access to the sky. Then ... oh wait ... the sunset is shifting towards those landmarks every day. Oh wait, now its turning around to go the other way.

The total span of movement is so large, that its hard to miss unless you are on a featureless landscape or in the open sea.

I am super impressed by humans noticing and separating the planet's from the stars. Look at those stars they don't twinkle and they move funny. I guess the planets drew attention because of their brightness and by their lack of twinkle.

I’m sure you’d know that this was winter. If you line 2 sticks up with sunrise, and keep adjusting them every morning, eventually you’ll see that the sun stops rising further south and starts moving north again. You don’t need complex mathematics to work it out.

For Orkney the difference in day length between winter and summer solstices is about 12 hours?

December: https://www.timeanddate.com/sun/uk/kirkwall?month=12&year=20...

June: https://www.timeanddate.com/sun/uk/kirkwall?month=6&year=202...

Where I live, the difference is almost six months!

So roughly your latitude is 40 degrees ?

Now if you disclose your local time offset from GMT, say, Palantir can send a drone carrying roses.

Of course this is meant as a joke, but wanted to emphasize how easy it is for location information to leak. And if one really doesn't care about collateral deaths how easy it is to exploit location data.

We’re I live it is a little bit more than 21 hours. Quite noticeable.

Why not just point the door to the north if the goal was to keep the sun out?

In Scandinavia we have no heat to anor condition out.

> When an aperture is aligned to the winter solstice, it is also aligned to avoid light the rest of the year. An early attempt at air conditioning?

In the northern latitudes, doubtful. It would be cool enough year round.