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

Civilization had already been around for thousands of years by 45BC…. the Great Pyramid dates from ~2500 BC. Sumerian civilization had 360-day calendar… same origin as where we get the 360 degrees in a circle, and 3600 seconds in an hour.