its just based off of a pattern
it doesnt make them prophets or anything...its just based off of the earths positioning around its orbit of the sun, as well as when the moon comes in between (or behind) that orbit (when the moons in between the earth and the sun its a "solar eclipse" and when the Earth is between the moon and the Sun exactly, its a lunar eclipse. Lot of other factors involved in it, but its a pattern. When u figure out the time in between, u can predict ahead of the time when the next one will happen
It wasnt like some guy woke up and had a dream, and wrote down all the dates of when they were going to happen. Its still impressive though for their time period
