Elemental Martian Calendars

Copyright © 2002 by Terry Phelan


Last fall, I attended a gathering of The Mars Society at MIT and brought with me a proposed calendar for the planet Mars that named 24 months after the elements of the periodic table, in order, from Hydrogen to Chromium. The advantages of this method are:

The list is logical and immutable. Everyone knows, or should know, which month is coming next. For those who don't, I've created a "Martian Calendar Song" that puts the month names into a simple mnemonic. Even if this scheme is not chosen, the song can help chemistry students memorize the first 24 elements.

The list is culturally neutral - based on science, not any particular language, constellation names, or order of letters in any particular alphabet.

The scheme simplifies the visualization of calendrical divisions other than the 24-month plan, which received some critical feedback at MIT. I have subsequently devised, in addition to the Chromium, alternative calendars for Mars known as the Potassium, Vanadium and Titanium, described below:

The CHROMIUM Calendar

Is the calendar I initially proposed. 24 months, the first 23 having 28 days. The month of Chromium having 24 or 25 depending upon leap year considerations. Each of the 28-day months is divided into four 7-sol Martian weeks with days named for the planets: Sunsol, Mercsol, Venusol, Earthsol, Marsol, Jovsol and Satsol. Holidays Uranusol, Neptunsol, Plutosol and the Leapyearsol form the final week of Chromium (Cr22 - Cr25). The year begins at the solstice that brings summer to the northern hemisphere and winter to the south, due to the fortuitous circumstance of the year's first 3 seasons added together being evenly divisible by 28. The Vernal Equinox thus occurs at the beginning of a month - Argon, the 18th month of the year.

This arrangement also adds a double meaning to the lyric line "Nitrogen, Oxygen, Fluorine - Breathe the first two out of three" in the Martian Calendar Song since the month of Fluorine just happens to coincide with the beginning of the dust storm season. To the best of my knowledge, this is the only proposed calendar to have a song associated with it.

The POTASSIUM Calendar

This calendar evenly divides the 95 working weeks of the Chromium calendar into 19 months of five 7-day weeks each (35 Martian days or 'sols' each) named for the first 19 elements of the periodic table - Hydrogen to Potassium. The weekday names are the same as for the Chromium calendar. Uranusol, Neptunsol, Plutosol and the Leapyearsol follow P35 as a year-end "week" which is not considered part of any month. These 4 sols may be abbreviated Ye1 through Ye4.

This calendar may be neatly aligned with the Martian seasons in either of two ways. Using Encyclopaedia Britannica data where winter (194 sols) and spring (156 sols) in the northern hemisphere total 350 sols (exactly ten months) the sensible place to begin this calendar would be at the solstice that brings winter to the northern hemisphere. Summer in the northern hemisphere would thus begin each year on the first of Sodium (Na1). If using the Zubrin calendar, which calculates 192 sols in northern spring, the calendar could alternatively start at the Autumnal equinox. Autumn, winter and spring, by Zubrin's reckoning, total 490 days (14 even months), allowing northern summer to begin each year on the first of Phosphorus (P1) as Mars enters the Zubrin month of Sagittarius.

The VANADIUM Calendar

This calendar uses the same day-of-the-week and month names as the Chromium calendar but divides the Martian year into 23 months of 29 Martian days or 'sols' each. The advantage of this is that 29 Martian days is just a few hours short of 30 Earth days, making the months of the Vanadium Calendar as close as possible to the actual lunar month on Earth in time duration. Only lunar calendars on Earth that alternate between 29 and 30 Earth days per month are able to achieve a closer approximation of this time period. The close approximation to Earth's lunar cycle may be advantageous to certain applications, such as calculating human pregnancies. It would also be the most adaptable to lunar calendars on Earth. The Islamic month of Ramadan, for instance, could occur almost precisely every 12 Martian months, twice in most Martian years.

The Vanadium calendar may also delight those who may despair of the simplistic rigidity that characterizes the other 3 proposed calendars with month names based on the periodic table. Those who might miss having months begin on different days of the week should revel in this calendar in which the starting dates of the various months cascade merrily backward through the week with only the months of Hydrogen, Oxygen, Phosphorus and Titanium beginning on a Sunday (or Sunsol). The 95th week of each year ends on Saturday (Satsol), V27, with Uranusday (Ursol) falling on V28, Neptuneday (Nepsol) on V29, Plutoday (Plusol) on V30 and Leapyearday (Leapsol) on V31, giving the final month of Vanadium 30 days on 668-day years and 31 days on 669-day years. The formula is easily expressed in a simple poem:

Should the Martian year end in double zero,
Two, four, six or eight,
Vanadium hath thirty days
To keep the calendar straight
But should the year end in single zero,
One, three, five, seven or nine,
Vanadium hath thirty-one;
All other months have twenty-nine.

No starting point exists which would allow more than one season to begin on the first of a month. Starting at the Vernal Equinox (H1), the Vanadium calendar would align with the Martian seasons as follows: Summer solstice (N21), Autumnal Equinox (Si24), Winter Solstice (K21).

The TITANIUM Calendar (a.k.a. "The Slackers' Choice")

This calendar features 22 months of 30 Martian days or 'sols' each ending with a 9 to 10 day long festival to honor the planets and stars at the end of each year. The sol names are slightly different for this calendar than for the other 3 proposed calendars that name the months after the periodic table in that each 30-day month is neatly divided into 5 weeks of 6 sols each.

The final eight to nine sols may be abbreviated as V1 through V9 - for Vanadium, the next element after Titanium, which is easier than abbreviating them Ye1 through Ye9 or Ti31 through Ti39, but as this does not constitute a full month, the calendar is called the Titanium Calendar for the last full month that it completes.

Unlike the Chromium calendar which was largely inspired by the International Fixed calendar of Moses Cotsworth and the Potassium and Vanadium calendars which owe their inspiration to an old article by Isaac Asimov in Fantasy and Science Fiction magazine, the Titanium calendar is an adaptation of a "Zero Mondays Slackers Calendar" mischievously proposed by yours truly for our planet Earth about a decade ago.

In keeping with the convention of referring to Martian days as "sols", the six sols of the Martian week would be named as follows: Sunsol, Tuesol, Wensol, Thursol, Frisol, Satsol

These names would apply for the first 659 sols. The final sol of Titanium, however, Satsol Ti 30, would become Mercsol, to honor Mercury. The final sols of the year would then become:

  1. Vensol, pronounced VEEN SOL, to honor Venus.

  2. Earthsol, to honor Earth.

  3. Marsol, (gotta be an important day on Mars).

  4. Jovesol, to honor Jupiter, or "Jove."

  5. Satursol, with an extra syllable to distinguish it from an ordinary weekly Satsol.

  6. Ursol, pronounced YOOR SOL, to honor Uranus.

  7. Nepsol, for Neptune, of course.

  8. Plusol, pronounced PLOO SOL.

  9. Unsol, pronounced YOON SOL, to honor the universe, though if another planet were yet to be discovered beyond Pluto, its name could be given to this sol. Unsol is basically the leap sol, occurring roughly 3 of every 5 years.

In contrast to the other 3 calendars listed above each of which features 475 'working' sols per Martian year (very close to the 476 or 477 per year for the 96 work week Darian calendar), the Titanium calendar has a mere 440 - largely due to the six sol week. That makes over 1/3 of the sols either a weekend or holiday, thus earning this calendar its somewhat derogatory nickname - "The Slackers' Choice".

The major advantage of this calendar is that each of the 22 30-sol months of the Titanium calendar is equivalent to 30.82472 Earth days, making months on Mars closely compatible with months on Earth (which average 30.43683 days each). The Martian year equals 22.57 Earth months on Earth calendars that divide the Earth's 365.242-day year into 12 months. If a project is due in three months on Earth, it is due (most of the time) in three months on Mars too.

Like the Vanadium calendar, no starting point exists which would allow more than one season to begin on the first of a month. Starting at the Vernal Equinox (H1), the Vanadium calendar could align with the Martian seasons as follows: Summer solstice (N15), Autumnal Equinox (Al13), Winter Solstice (A5). Both equinoxes would thus regularly occur on a SUNsol.