Astrophysics can be said to have been founded by Johannes Kepler around the year 1600. He based his break-through science on data of the position of Mars in the sky and disproved the ancient ideas about circular orbits and epicycles.
But why wasn't this done far earlier, by using observations of the Moon? Wasn't it pretty obvious to a careful astrologer a thousand years ago, that the Moon does not have a circular orbit and does not describe epi-cycles? It is the easiest celestial object to observe, visible both night and day. Moon calendars may have been designed tens of thousands of years ago, there's no lack of observational data. Kepler instead used a few oppositions of Mars which take place only once every two+ years. Since the Moon is the one object which does orbit Earth, in a geocentric world view it should've been the perfect test of circular and epi-cyclical theories about its orbit. Its nearness causes a daily parallax between moonrise and moonset, but that wouldn't be beyond a genius like Kepler or many mathematical astrologers before him.
What made the orbit of the Moon difficult for the ancients to understand?