Darian calendar variants

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All variants of the Darian calendar have some common properties derived from the original:

  • The Martian year (called mir) is divided into 24 months of approximately equal duration
  • Have 7 or 6 days per week, and 27 or 28 days per month
  • The year is 668 martian sols long
  • One leap day, at the end of the leap year
  • It has an accuracy of 7750 years
  • Begins the year on the vernal equinox
  • Each month begins on the first day of the week, and hence so does each mir. The week at the end of each quarter contains only six days. So, it has cycle of perpetuity of 28 days.

Original Darian calendar

Created by Thomas Gangale, it was first published in a paper in 1986. It was names after the author's son, Darius.

A mir is divided into 24 months, resulting a mean month of 27.8579 sols. It is probably much easier for humans to adjust to a slightly shorter month than to accept one that is nearly twice as long, as in other calendars with 12 months.

In the Darian calendar, common years of 668 sols contain 20 months of 28 sols and four months of 27 sols. The 27-sol months occur at the end of each quarter. In leap years of 669 sols, the last month of the year (which also ends the fourth quarter, of course), instead of containing 27 sols, is a normal length of 28 sols. The leap sol is therefore the last sol of the year, rather than being stuck somewhere in the middle as it is on Earth's Gregorian calendar.

Names of the months come from the names of constellations through which the sun appears to pass as seen from Mars during the course of a year. But there are only 12 such constellations, so two names must be used for each constellation. Thus, the first name is the latin name of the constellation, while he second it's the Sanskrit name.

The fact that a martian month has 28 or 27 days makes it even more easier to implement weeks on Mars than Earth. The Latin names of the days of the week are prescribed as a starting point: Dies Solis, Dies Lunae, Dies Martis, Dies Mercurii, Dies Jovis, Dies Veneris, and Dies Saturni.

By choosing the Martian vernal equinox occurring on 1609 March 11 as the epoch for the Darian calendar, any recorded telescopic observation of Mars can be expressed in a common chronological reference system without negative values.

Areosynchronous Calendar

Created by Shaun Moss.

It is identical in structure with the Darian calendar, but with an alternative system of month and day names.

Months are named after the Rotterdam Monthnaming System, but weeks have the names (in order): Heliosol, Neriosol, Libersol, Terrasol, Venusol, Mercusol, Jovisol. The terms Neriosol and Libersol appear instead of Phobosol and Deimosol, which translated would mean "Fear Day" and "Terror Day". (see also: Renaming of Mars' Moons).

Darian Defrost Calendar

Created by Frans Blok.

Identical as structure to the original Darian calendar, but with month and day names based on the Rotterdam system, to eliminate any cultural bias, thus making it probably the best choice for a calendar.

Leap mirs for Darian calendar variants

  • If the mir is odd then it is a leap mir having 669 sols (an odd number). This rule accounts for 5000 leap mirs per 10000.
  • If the mir is divisible by 10 then this also is a leap mir (in most cases - see following rules). This rule adds a further 1000 leap mirs per 10000, totalling 6000.
  • BUT, if the mir is divisible by 100 then it is not a leap mir. This reduces the number of leap mirs per 10000 by 100, bringing us back to 5900.
  • BUT, if the mir is divisible by 500 then it is a leap mir. This accounts for 20 more leap mirs per 10000, bringing us to a total of 5920.

Month names for Darian calendar variants

24-Month Naming Conventions Latin/Sanskrit zodiacal Alphabetical artificial
(Darian Defrost and Areosynchronous)
Season + numerical prefix

(Darian Hensel)

1st Month Sagittarius Adir Vernalis 28
2nd Month Dhanus Bora Duvernalis 28
3rd Month Capricornus Coan Trivernalis 28
4th Month Makara Deti Quadrivernalis 28
5th Month Aquarius Edal Pentavernalis 28
6th Month Kumbha Flo Hexavernalis 27
7th Month Pisces Geor Aestas 28
8th Month Mina Heliba Duestas 28
9th Month Aries Idanon Triestas 28
10th Month Mesha Jowani Quadrestas 28
11th Month Taurus Kireal Pentestas 28
12th Month Rishabha Larno Hexestas 27
13th Month Gemini Medior Autumnus 28
14th Month Mithuna Neturima Duautumn 28
15th Month Cancer Ozulikan Triautumn 28
16th Month Karka Pasurabi Quadrautumn 28
17th Month Leo Rudiakel Pentautumn 28
18th Month Simha Safundo Hexautumn 27
19th Month Virgo Tiunor Unember 28
20th Month Kanya Ulasja Duember 28
21st Month Libra Vadeun Triember 28
22nd Month Tula Wakumi Quadrember 28
23rd Month Scorpius Xetual Pentember 28
24th Month Vrishika Zungo Hexember 27-28

Day of week names for Darian calendar variants

7-day Naming Conventions "Sol" + Latin Alphabetical artificial + "sol"
(Darian Defrost)
Latin + "sol"
1st Day Sol Solis Axatisol Heliosol
2nd Day Sol Lunae Benasol Phobosol
3rd Day Sol Martis Ciposol Deimosol
4th Day Sol Mercurii Domesol Terrasol
5th Day Sol Jovis Erjasol Venusol
6th Day Sol Veneris Fulisol Mercurisol
7th Day Sol Saturni Gavisol Jovisol

External links and references