Keeping Time at Stonehenge
cambridge.org
cambridge.org
> In The Light Ages, Cambridge science historian Seb Falk takes us on an immersive tour of medieval science through the story of one fourteenth-century monk, John of Westwyk. From multiplying Roman numerals to navigating by the stars, curing disease, and telling time with an ancient astrolabe, we learn emerging science alongside Westwyk, while following the gripping story of the struggles and successes of an ordinary man in a precarious world. An enlightening history that argues that these times weren’t so dark after all, The Light Ages shows how medieval ideas continue to color how we see the world today.
* https://www.goodreads.com/en/book/show/50489364-the-light-ag...
* https://wwnorton.com/books/9781324002932
Has a chapter or two of keeping the calendar:
* https://en.wikipedia.org/wiki/Liturgical_year
and actual time for daily services:
* https://en.wikipedia.org/wiki/Liturgy_of_the_Hours
It should also be noted that for time periods measured over millennia, one may also keep in mind that there are subtle changes in the night sky because of the wobbling of the Earth on its axis of spin:
* https://en.wikipedia.org/wiki/Axial_precession
So that (e.g.) the North Star that we have today (Polaris) is not what not the same as in the past, and will change in the future:
* https://en.wikipedia.org/wiki/Pole_star
The Hoover Dam in the US actually makes use of this astronomical fact in a monument to indicate to possible future generations when it was built:
> But that point near Polaris, which we call the North Star, is actually slowly moving and tracing a circle through the night sky. While Polaris is our North Star, Hansen’s terrazzo floor points out that the North Star of the ancient Egyptians, as they built the great pyramids, was Thuban. And in about 12,000 years, our North Star will be Vega. The workings of this precession are best explained with an animation, as in figure 1. Here you can see how the axis of the earth traces a circle in the sky over the course of 25,772 years.
* https://medium.com/the-long-now-foundation/the-26-000-year-a...