A grouping of granite blocks along a grassy Amazon hilltop may be the vestiges of a centuries-old astronomical observatory ....The 127 blocks, some as high as 9 feet, are spaced at regular intervals around the hill, like a crown 100 feet in diameter. On the shortest day of the year -- December 21 -- the shadow of one of the blocks disappears when the sun is directly above it.
...(P)ottery shards near the site indicate they are pre-Columbian and maybe older -- as much as 2,000 years old.
....Last month, archaeologists working on a hillside north of Lima, Peru, announced the discovery of the oldest astronomical observatory in the Western Hemisphere -- giant stone carvings, apparently 4,200 years old, that align with sunrise and sunset on December 21.
I think that's pretty cool, and I have to wonder how I missed last month's discovery as well.
I think any observant person would notice that the sun doesn't rise and set in the same place all the time. And a really curious person might try to mark off the extremes, and then try to time the interval. If the really curious person is a high ranking priest or noble, once he (you know it was a he) figured it out, why not put something BIG to mark it, rather than a carved stick or pile of rocks? You'd need to know where to stand to see what you were looking at....so you'd need two objects for every viewpoint (it takes 2 points to make a line). Why not make one an arch to look through and another a stone to stand on?
And then, of course, you'd have to do ceremonies, because that's what the plebs want, so you come up with an elaborate ceremony about some cluster of stars and the sun rise and then your grandson notices that the stars aren't lining up anymore and he talks it over and makes some notes and HIS grandson "discovers" precession of the Equinoxes.
There, wasn't that easy?
Of course, Precession has stopped, hasn't it? I have to look more into this still.