Eli5: How did ancient civilizations in 45 B.C. with their ancient technology know that the earth orbits the sun in 365 days and subsequently create a calender around it which included leap years?

Question

Eli5: How did ancient civilizations in 45 B.C. with their ancient technology know that the earth orbits the sun in 365 days and subsequently create a calender around it which included leap years?

In: 6494

Answer 1

It’s important to also remember that the calendar is one of the most critical pieces of technology for agriculture. When to sow, when to harvest, how large your reserves need to be, when to prepare for flooding, when to store water. All of those are centered around the calendar. So over thousands of years it makes sense that people would invest the time into documenting and studying it. Because it is so critical to survival

Fine details like leap years happened a lot later though.