The ancient monuments saluting the winter solstice
9 comments
·December 22, 2025voidUpdate
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
arethuza
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!
srean
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 sun set 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.
akssri
In India,
https://www.etvbharat.com/english/bharat/padmanabha-swamy-te...
Kerala, for the curious, is also the place where the infinite series (and with it arguably calculus) was devised some 200 years before Newton's birth.
Blatant Western-centrism within academia (and the strange, almost primitive-hatred for living ancient-cultures) perhaps hasn't led either to the recognition of "ancient" monuments in India or its scientific/astronomical outputs.
The festival of Sankranti for eg. is so old that due to the Hindu Luni-Solar calendar's usage of the sidereal year, it has drifted off from the winter-solstice by 20 odd days, starting from 150 BC (amusingly as has the Julian calendar, but due to a lack of precision in arithmetic / observational accuracy).
srean
Depends on the details of how you define calculus. Archimedes was doing integration, Descartes was evaluating slopes and tangents of algebraic curves. Isaac Barrow had a good grasp of fundamental theorem of calculus, that differentiation and integration are inverse operations. Brook Taylor did Taylor series before Newton.
Newton and Leibnitz get credit because they placed calculus as a general technique that is immensely broadly applicable not just to extrapolate the tangent function or the some function but to any function that's smooth in some sense. They worked out the details that do not depend on the specifics of the function especially how to push the differential and integral operators through +,-,×,÷ and function composition sign. It did not matter what the function was as long as it was built up from those operations.
I am familiar with the work of Kerala school and also of Aryabhatt's work on using differential coefficients to extrapolate the sin function (this being much before Kerala school), his work on difference equations.
Rather than getting caught up with us versus them narratives , spend some time learning about the beauty of math and how different cultures have thought about them in such creative ways. Otherwise you risk sounding uneducated, ignorant and rageful.
my modern equivalent(I needed last year for surfing (after i needed to cut a surf trip short as it became night))
https://daylight.franzai.com/