The Darian Calendar at a Glance

Notes:

1. Each month begins on the first day of the week. The week at the end of each quarter contains only six days.

2. An extension of the Darian calendar includes timekeeping systems for Io, Europa, Ganymede, Callisto, and Titan.

3. Variants are:

   • Areosynchronous - Identical in structure, with an alternative system of month and day names.

   • Darian Defrost - Identical in structure, with an alternative system of month and day names.

   • Darian Hensel - Identical in structure, with an alternative system of month names.

   • Heron - Uses the same pattern of 27-day and 28-day months; however, all weeks contain seven days, making the calendar non-perpetual. The calendar year begins 13 days after the winter solstice, instead of on the vernal equinox. Uses an alternative system of month and day names.

   • Martiana - Uses a biennial cycle similar to the Aitken calendar to repeat the relationship of the days of the week to the month. All weeks contain seven days.

   • Naughton-O'Meara - 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. Uses an alternative system of month and day names.

   • Utopian - Identical in structure, with an alternative system of month and day names.

4. Closely-related, independently-developed calendars are:

   • Hollon - Identical in structure, but without a defined epoch. Uses a different system of month and day names.

   • Schmidt - Uses a different intercalation scheme (involving 670-sol and 671-sol leap years), and does not have a defined epoch.

5. This is one of several Symmetric Vernal Equinox Martian calendars, which generally have the following characteristics:

   • Divide the Martian year into 24 months of approximately equal duration.

   • Retain the seven-day week.

   • Begin the year on the vernal equinox

   • Place the leap day(s) at the end of the year.

6. Other types of 24-month calendars are:

   • Symmetric Double Gregorian Martian calendars

   • Asymmetric Vernal Equinox Martian calendars

   • Symmetric Summer Solstice Martian calendars

			The Darian Defrost Calendar Frans Blok
			The Rotterdam Month and Weekday Naming System Frans Blok
			Waar blijft de tijd op Mars? Frans Blok
			The Darian System Thomas Gangale
			MarsView Joe Knapp
			The Utopian Calendar Mars Time Group
			The Areosynchronous Calendar Shaun Moss
			The Kepler Calendar Shaun Moss
			Martian Time
			Martian Time Survey 2.2