Astronomy and calendar in ancient Rome

An investigation into the astronomical foundations of the archaic Roman calendar reveals a sophisticated, pre-established system underlying early state religion. Challenging traditional views of the Numan calendar as purely agricultural, this study demonstrates that Roman ceremonial dates systematically encoded precise celestial periodicities, including the motions of the Sun, Moon, and Venus. Central to this framework is the 24-year Numan intercalation cycle, which harmonizes multi-body planetary movements while meticulously tracking eclipse cadences. Through the exegesis of ancient literary texts, mythic narratives, and ritual practices, key festivals—such as the Matronalia, Anna Perenna, and October Equus—are reinterpreted as designated markers for the Saros cycle and the nodal revolution of the Moon. The findings situate archaic Roman timekeeping within a broader Near Eastern scientific lineage, illuminating an enduring cultural and astronomical link between early Rome and Mesopotamia.