Thanks, Jeff! The key to the Periodic Calendar is identifying that there are seven types of years, depending on the day of the week that starts it off. At first I thought I needed to make 7 calendars to cover the possibilities, but my aha moment came with the idea of the Gregorian Isotopes, which flip our focus from the day of the month to elements based in days of the week that exist on an array of days of the month.

The core idea is that August 10th is a semi-meaningless count of the days, whereas the real information lies in today being Sunday.