Twitter bots offer the possibility of seeing beyond our narrow timeline, and offering a glimpse of other systems of timekeeping. The Mayan calendar composed of interlocking cycles, which only vaguely match the solar year, the base for most Western systems.
The Babylonian calendar has its roots in Mesopotamia systems reaching back to the 2nd millennium BCE. It's structured around the Metonic cycle, the 19-year period when solar and lunar years match. Babylonian timekeeping became the standard in the empires established after the conquests of Alexander the Great. It fell out of active use in the 14th century, making it the longest continuously used calendar system. Along the way it heavily influenced the Roman and Jewish calendars.
While the Mayan calendar is relatively well known, the calculation of a analeptic, or forward-projection, Babylonian calendar is novel. Both bots are powered by convertdate, a Python module maintained by the author.