With that convoluted title I’m making myself think about what we’d call the additional days on other planets or other different temporal circumstances.
Instead of ending them with -day you could end them with the planetary body name or circumstance name. Today might be Lajove on Jupiter!
The beginning of the end of Earth-week? I guess it’s time to ride the cosmic waves to eternity then.
Ride those celestial surfboards through the 'verse!