SUMMARY
4) The Solarian Calendar on One Page

Earth lets one calendar do two different jobs.

It organises human life and describes the planet's orbit.

Across the Solar System, those two clocks rapidly separate.

Solarian's answer is to separate the jobs — then connect them where useful.

THE HUMAN CALENDAR

1 civil day
Normally 86,400 seconds. Mars keeps its natural sol.

1 week = 7 civil days
The common short recurring rhythm.

1 minth = normally 4 weeks
The human-scale operating period.

1 mear = 12 minths
The larger recurring operating cycle.

The principle is: The mear belongs to operations and people.

THE ASTRONOMICAL CALENDAR

1 orbital year = 1 heliocentric orbit

1 orbital month = 1/12 of that year

The twelve orbital positions share one common orientation around the Sun.

The principle is: The year belongs to the orbit and planet.

THE CONNECTING BRIDGE

Where the two calendars fit cleanly together, one integer connects them:

R = minths per orbital month = mears per orbital year

So:

Mars = R2 >> 2 operating mears fit exactly into an orbital year
Ceres = R5 >> 5 operating mears fit exactly into an orbital year
Jupiter = R13 >> 13 operating mears fit exactly into an orbital year
Saturn = R32 >> 32 operating mears fit exactly into an orbital year
Uranus = R91 >> 91 operating mears fit exactly into an orbital year
Neptune = R179 >> 179 operating mears fit exactly into an orbital year

The same human calendar simply repeats more times as the planetary year becomes longer.

Where synchronization does not help — as on Venus and Mercury — the human and astronomical calendars run independently.

THE NECESSARY FLEX

Real orbits do not divide perfectly into weeks.

Solarian absorbs the remainder through controlled whole-week expansion joints.

Minths may occasionally contain three or five weeks instead of four.

But: Solarian never breaks the week.

THE COORDINATING GRID

Standard-day settlements share one continuous weekly sequence.

The Solarian Week Index — SWI simply counts those weeks, giving different local calendars a common operating coordinate underneath.

Mars keeps its sol-based week and maps deterministically to the same common chronology.

THE IDEA UNDERNEATH EVERYTHING

One human cadence. Many local astronomical calendars.

Human time stays human.

Orbital time stays astronomical.

Synchronise them where that helps.

Let them separate where it does not.

Preserve local culture above a small shared grammar.

Common structure; local culture.