The Robinson 24-Month Calendar at a Glance

Notes:

1. The year count increments on the terrestrial cycle, which means that the number of the year changes once or twice during the Martian year, and the dates on which these changes occur varies from year to year.

2. The calendar is similar in structure to the Darian calendar, but was developed independently. Differences are:

• Uses a different pattern of 27-day and 28-day months.

• The epoch is based of a fictional event (30 Apr 2026 CE).

• The calendar year begins 4 days after the wihter solstice, instead of on the vernal equinox.

3. This is one of several Symmetric Double Gregorian Martian calendars, which generally have the following characteristics:

   • Divide the Martian year into 24 months of approximately equal in duration to encompass the longer Martian year.

   • Retain the seven-day week.

   • Begin the year near the Winter solstice

   • Place the leap day(s) in the fourth month.

   • Base the month names on the traditional Roman names, plus some additional naming scheme

4. Other types of 24-month calendars are:

   • Asymmetric Vernal Equinox Martian calendars

   • Symmetric Summer Solstice Martian calendars

   • Symmetric Vernal Equinox Martian calendars

		Excerpts from Red Mars Kim Stanley Robinson
		Robinson LS Calendar
		Robinson 24-Month Calendar
		Martian Time
		Martian Time Survey 2.2