Imagine a calendar that is the same every year—sort of.
Calendars are fundamentally weird—after all, none of the many divisions of time we use can be accurately and consistently pegged to the movements of the Earth, Moon, planets, and stars. A day is pretty close to the actual time it takes the Earth to make one full rotation, but that varies based on where the planet is in its orbit, a few seconds either way. The week has absolutely no connection to anything; a month is a variable unit of time that we just sort of guess at. […]