Can Venus keep a calendar?

That time, that place

The Maya cities of Mesoamerica had writing, a place-value number system, and temples built to serve as instruments of observation. It was a body of knowledge raised entirely apart, having never met Eurasia.

Why this question

Venus is an awkward object. It rises as the morning star, disappears for a while, then returns much later in the evening sky. Does this coming and going follow a rule?

What was found

Maya astronomers put Venus's return at 584 days. The modern figure is 583.92. That number can only come from stitching together the observations of several generations.

The Dresden Codex carries a Venus table, and the remarkable part is how it handles error: knowing the table would drift from reality over time, they wrote in when and by how much to correct it. They knew their own calculation was not perfect.

They used zero as well — with no connection to India whatsoever, on their own.