I mean, at some point (hopefully) humans will be living on more than one planetary body in the solar system. Once you have people on Mars and Earth, you're nev

I mean, at some point (hopefully) humans will be living on more than one planetary body in the solar system. Once you have people on Mars and Earth, you're never going to harmonize the two, without shifting both to the same orbit. So you could just give up on having the planet's orbit define the calendar, design a pleasing civil calendar for your civilization that is probably roughly a Earth year long, but without all the hacks to make it exact or synchronized, and just let your cell phone add a calendar event for when spring, etc starts.