It is exactly for this reason that Easter forced the church to pour resources into Math and Astronomy.
Jewish calendar is fully lunar, so determining the date of passover was extremely easy. Lunar calendars around the world assigns full moon on the 15th of every lunar month. So at the full moon of a certain month, that’s passover, end of story, easy-peasy.
But at a certain point the they decided passover should fall after the vernal equinox. Then church somehow decided that Easter has to be on a sunday. So the sunday after the fullmoon after vernal equinox, and then something about if vernal equinox is also a full moon, then they have to do something special all together. That’s all after translating the date of the full moon to a solar calendar where dates are fixed to equinox and solstices and not the cycle of the moon.
The concepts of “Full Moon” is from Lunar cycles, and the concept of “Equinox” is from Earth rotating around the sun at an angle. It is essentially impossible to connect the two separate mechanisms together without a total understanding of the actual physics/mathematical model.
The ancients thinks that all these things are related (hence assigning 12 months (concept of moon cycles) to a year (concept of earth rotating around the sun). But since these two systems actually have very little to do with each other, thing just starts falling apart.
They certainly can’t get the correct answer if the model is Earth at the center and moon and sun rotates around the earth.
It is for this reason how church people like Copernicus came to be. When Jesuits and Dominican priests came to Asia, everyone of them seemed to have an understanding of astronomy and how to make the calendar more accurate, and how reconcile lunar and solar calendars. The current version of Chinese calendar is actually defined by the priests. That’s all because they had to learn how to calculate the date of Easter.
