Party Planning the Next True Happy New Year: Lunar Orbital Evolution Epochs with Integer Synodic Months Per Year

Abstract: Humans like to party, and New Year celebrations are a great way to do that. However New Years celebrations that rely on an orbital year don't line up with those that use a Lunar Calendar, as there are currently 12.368 synodic months (moonths) in a year. There is cyclostratigraphic, paleontological, and tidal rhythmite data that reveal that over billions of years the interplay of angular momentum between the Sun, Earth and Moon has changed the rate of rotation of Earth, and at the same time evolved the orbit of the Moon, and therefore the length of a Lunar month. Using a subset of this data and referencing literature models of the Moon's orbital evolution, we create our own simple model to determine "True Happy New Years", time periods when there were an integer number of lunar synodic months in an Earth orbital year. This would allow modern calendars to pick a shared New Year's Day, and party accordingly. We then predict the next True Happy New Year to be in 252 million years, and offer suggestions to begin the party planning process early, so that we as a planet may be ready.