How did ancient cultures know when the solstice was? If you didn't tell me it was the 21st, I don't know how I'd be able to tell you other than by carefully measuring the sunrise and sunset times
Also fun fact: date of latest sunrise is slightly out of phase with seasons https://xkcd.com/2792/
Merry Sun-Fence Day everyone. ;-)
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.
The sheer amount of _stuff_ in the sky is mind boggling, the silence is deafening.
That we spend all of human existence until little over a century ago living like that is something I have a hard time wrapping my head around.
Edit: Obviously somewhere like here in Scotland observing the sunrise is easier said than done - particularly at this time of year!
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.
https://en.wikipedia.org/wiki/Solstice#Solstice_determinatio...
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.
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.
I find it strange that today knowing much more about sun and moon we don't consider them as gods. Today we know for sure they are the origin of all life on this planet and yet many cultures decided to go for an abstract intangeable entities instead of what is directly in front of us and can't be debated.
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.
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.