This document is part of the Martian Time Boneyard. It was originally located at
Author: Mark Knoke

Towards a Better Martian Calendar

Mark Knoke

Upon hearing of Robert Zubrin's Martian calendar, I was pleased to learn that others showed similar interests as me -- namely Mars and calendars. But as I read an explanation of Zubrin's calendar, several problems jumped out at me. First was the variety of lengths of the months. They varied from 46 sols to 66! (A 'sol' being the Martian equivalent of a Earth day.) How will a Martian remember all those lengths? "65 sols hath Cancer and Virgo. All the rest have 66, except Gemini which has 61 and Libra which has 60 and Taurus which has 56 and Scorpius which has 54 and Aries which has 51 and Sagittarius which has 50 and Pisces which has 48 and Capricorn which has 47 and Aquarius which has 46." ...It seems to lose the rhythm towards the end, wouldn't you say?

I then noticed that the year began on Gemini 1, which he places at the Vernal Equinox. This seemed odd, since I'm used to Aries beginning the Zodiacal year.Then I realized that this was very geocentric of me, since Aries and the sun line up in the Spring only if you're on Earth. So it would make sense if Mars had a different timing for the constellations. In fact, Sagittarius is the Zodiac constellation that the Sun is in at Mars's Vernal Equinox. But lo and behold, Zubrin puts Sagittarius as the first month of Autumn! Instead of naming the constellation that the Sun is in from Mars, he names the constellation that Mars is in from the viewpoint of the Sun. Who's on the Sun to care about this? If this is supposed to be a Martian calendar, why isn't it areocentric? If we did the same on Earth, a person born October 14 would no longer be a Libra, but an Aries! Confusing, no?

That is why I decided to invest a little more thought and effort into my own Martian Calendar. I knew I could design a better one. My first attempt several years ago, the Marvinian Calendar, preserved the 30 and 31-sol lengths of the months, thus producing a 22-month year. For the extra ten months, I chose from the Zodiac, placing Aries between March and April, Cancer between June and July, and so on. I now see this as a mistake. Actually, I see two glaring errors with the Marvinian Calendar. Besides the possibility for confusion by using Zodiac constellation names, there was also a problem with the number of months: 22 could only be divided in half (or elevenths!). A quarter-year would be 5-1/2 months long, and that just ain't pretty. Twelve months per year would be ideal since we're already accustomed to that number. This, however, would leave the months at 55 and 56 sols long. If a 31-day month can drag on forever, imagine suffering one twice the length. It would seem as if time were standing still! Another possibility is 24 months of 27 and 28 sols. I was immediately put off by this idea since it reminded me of 13x28 Earth calendars. Artificial and repetitive. And when you mention dropping a Saturday every 27-sol month, I shudder.

Naming 24 months would also be problematic. At least twelve new names must be found. Avoiding the Zodiac ("Aquarius is *when*?"), we could delve into foreign languages (January, Janvier, February, Fevrier, ...), we could use nonsense words (Atnough, Bithogin, Kupf, Gysle, ...), or we could even borrow the Zodiac constellations from a non-Roman culture -- Sanskrit, perhaps? Alas, these would still be nonsense words to the vast majority of any world. Multiple languages would certainly cause confusion during translations, so that's out as well.

Perhaps, I thought to myself, if we minimize the number of new month names, but also minimize the length of the months, we could arrive at a happy medium? Well, then: 16. Only four new month names to learn, only 41 or 42 sols in a month (only 33% more than we're used to!), and it's easily divisible by four! Of course, Zubrin would complain that each set of four months doesn't align with each season. But I say that people could more easily remember the dates of four equinoxes and solstices than remember the eleven lengths of months in his own calendar. After all, what will children need to know first: the number of sols in a month or the date of the beginning of summer? ("I'll meet you on the 57th of Pisces, okay?" "But Pisces only has 48 days, you fool!" compared with "I'll meet you on the 42nd of February." "Do you mean the 41st of February or March 1?") People will realize when the winter is approaching without needing to know the exact date and time!

So instead of twelve or 24 months using names of groups of stars, I arrived at sixteen months using the names of our current months plus four new ones. After all, it is better to create new words for new meanings than have multiple conflicting definitions for one word. If I used "vexillology" to mean "lexicography" also, that could cause some confusion. And so, it is necessary to coin new terms. Between March and April shall be Geldof. Between June and July shall be Yorte. Between September and October shall be Herjber. Between December and January shall be Vidman. I created these names as needed while designing Earthly calendars over the past years. (Actually, Geldof was first used as a month in an episode of the British television show _Red Dwarf_, but I liked the sound of it.)


January has 42 sols
February has 41 sols
March has 42 sols
Geldof has 42 sols
April has 42 sols
May has 42 sols
June has 41 sols
Yorte has 42 sols
July has 42 sols
August has 42 sols
September has 42 sols (41 in leap years)
Herjber has 42 sols
October has 42 sols
November has 41 sols
December has 42 sols

Several questions remain: "What *about* leap years?", "When is January first?", and "How do you plan on counting these years, anyway?" In answer to the first question, I must point out that the Martian year is approximately 668.5921 sols. The simplest mathematics I could find to simulate this fraction with whole numbers is as follows: 669 - 2/5 - 1/125 +1/10000 = 668.5921. Basically, 669 sols in a year except two out of every five which have 668, plus one additional year of every 125 also has 668, except one every 10,000 years which reverts back to 669. That last part won't be used any time soon, that's for sure! The pattern would proceed ABABA-ABABA-ABABA, with the occasional ABABB thrown in. Years ending in 2, 4, 7, and 9 would have 668 sols in them.

January 1 should be relatively soon after the Winter Solstice. If we set July 1 on the Summer Solstice, we achieve this goal since Winter would begin on Vidman 28. The Vernal Equinox would occur on Geldof 16 and the Autumnal Equinox would be on October 11. Unlike Zubrin's calendar, this calendar would begin in Winter, with January. This should not be an astrological nor astronomical calendar, but a commonly useful one.

Year one should include an important date in the human exploration of Mars. I would think that the landing of Viking I is an ideal candidate. Zubrin begins his numbering when his pattern of months and sols coincides with the Gregorian calendar. This is arbitrary at best. If we place Viking I's landing in year M1, then we are now in year M13. I'm sure there are people who would like to start with year zero, but that just doesn't work! It is the *first* year of exploration, not the zeroth year! If you really want a year zero between one and negative one, it should be the year *prior* to Viking I's landing. For example, Mariner 4 flew by Mars six Martian years before Viking I landed. This would be year M(-5). (1 - 6 = -5 !) That should please the traditionalists as well as the mathematicians!

There are a wide variety of Martian calendars already in existence. Some have familiar names for the months while others pride themselves on using completely different words. Some have months that are easily calculated while others just wouldn't be useful in the real world. In my mind, I group these into categories: Familiar/Useful, Semi-familiar/Useful, Different/Useful, Familiar/Non-useful, Semi-familiar/Non-useful, Different/Useful.

Zubrin's calendar would definitely fall into the S/N category -- familiar terms used oddly and varying-length months. Other S/N calendars are Forward's calendar with only the 4 seasons as months and Suran's calendar of Duodecembers and the like with months switching between 21 and 28 sols.

An example of an F/N calendar would be Strom's calendar of twelve Gregorian-named months of 55 and 56 sols -- a month that long just wouldn't be comfortable! Another would be my Marvinian calendar -- 22 months just wouldn't be useful.

D/N calendars include Rohrer's calender and Becker's calendar of 19 (!) months of 35 sols with months named after the Greek alphabet or the planets and moons of the solar system in a variety of languages. Sherwood's D Calendar also falls into this category, with months named after bright stars varying from 23 to 34 sols.

The S/U category would include Robinson's calendar of 24 equal months named after the Gregorian months in pairs: 1 January 28th followed by 2 January 1st. Aitken's calendar is similar to my own as far as the numbers are concerned (16x41/42), but he does not name the months except as "First Quarter of Spring" and so on.

D/U calendars are most prevalent. The Darian Calendar is a prime example of this category. The number and lengths of months is quite simple, but the month names would take some getting used to. Blok's Rotterdam Calendar is similar, except he invents 24 new names instead of using Roman and Sanskrit Zodiac names. The Millennium Mars Calendar also falls into this category. 20 months per year works as well as having 12, 16, or 24. They honor an assortment of Greek gods for their months, however.

As for F/U calendars, there aren't any. Except, of course, for mine. Sixteen equal months -- not too many, not too few. Only four new month names -- easy. I shall dub it the Vophick Calendar!

For further information, a comprehensive Martian calendar webpage is at Gangale's Mars Page.

Truthfully, I enjoy new and different names for months. I just don't see them being adopted by large portions of the population.

My response to further questions

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