# Calendar for Mars

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Xylene, Mar 31, 2012.

1. ### XyleneValued Senior Member

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There are 669 days in the Martian year (that's Martian days, which are about forty minutes longer than Earth days--there are 687 Earth-days in a Martian year.) We could have 20 months of 33 days each, with a 9-day Spare Time Week at the end of the year (STW doesn't fit into any year but just sits on its own at the end of each year).

The other alternative is to have 11 months with 33 days and 9 months with 34 days...just an idea.

3. ### Epictetushere & nowRegistered Senior Member

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That's all fine, but I suppose the point of all this is you are assuming we would be living there. Am I right? So remember that earth creatures have their own Circadian rhythms. For example, when the French Revolution was freshly made, the new government tried to institute a ten-day week as it was nicely metrical and all, nine days working and one day of rest, but after a short time even the horses were collapsing in the streets! We of the third rock from the Sun have hearts that beat to a different rhythm. So rather than considering how to divide a Martian day, think about how to make it work for us. man is the measure of all things, yada yada yada.

5. ### XyleneValued Senior Member

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1,398
I'm not suggesting longer weeks would become the norm...I suggest instead that STW could become a 9-day holiday. The other alternative I was thinking about was the possibility for 19 months of 35 days each (five normal-length weeks). This would mean that each month would start on Monday and end on the 5th Sunday following. 35 x 19 = 665 days, plus a short STW of only four days, more like a long weekend than an extra-long week.

7. ### Electro522Registered Senior Member

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Ok, so you have the calender worked out, what about the clock? You said it yourself, Mars' day is longer than Earths. The extra time would tremendously throw off our 24 hour clock.

8. ### Boris2Valued Senior Member

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the martian day is 24hr 37min so i reckon we could adapt.

9. ### Fraggle RockerStaff Member

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Actually our internal clock is set for something like 24.3 hours. In experiments people have been isolated in chambers with no windows, no clocks and no contact with the outside except via a team who were trained to not give any clues about the external time. They settled into a circadian rhythm slightly but distinctly and consistently longer than the 24-hour day.

So that would be the least of our problems on Mars. I think many people would be much more perturbed by never, in their entire lives, being able to go out into the natural environment. I'm not exactly a nature-lover, but I know that would get to me after a while.

10. ### Epictetushere & nowRegistered Senior Member

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Well, in the old Sci-Fi film Robinson Crusoe on Mars, they had chewable oxygen pills that allowed the protagonist to go wherever he liked without even a helmet. I have some free time this weekend, I could invent them if you like.

11. ### Robittybob1BannedBanned

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You have to be very careful with them. I found if they disolve too fast you became very gassy. What with the burping and the passing of wind the swallower became downright dangerous in public places.

12. ### Robittybob1BannedBanned

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That would be quite handy as you would no longer have any excuse for not getting your tasks done today.

13. ### Robittybob1BannedBanned

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10 days in week 6 weeks in month 11 months in year Plus 9 days holiday
= 669

14. ### Janus58Valued Senior Member

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2,214

As long as we are playing around with ideas, Let's try to tie the Martian "month" to its moons(or at least one of them), just like the Earth month is based on its Lunar period.

Now we can't just use a full moon to full moon
period, because for both moons, this is quite a short period. So instead, lets try the synodic period(meridian to meridian) of one of the moon's.

Deimos has the longest period, so we'll try that. It turn's out to have a synodic period of ~5.4 sols, This means that every 54 sols Deimos crosses the meridian at about the same time of the sol. If we use this for our basis for a month, we get 12.37 Deimos months per martian year.(compared to 12.36 Lunar months per Earth year)

12 months of 54 days each leave us short 20 days of a full Martian year(more accurately, 20.6 as there are 668.6 sols to a Martian year, but we'll touch on that later) spreading these out to our 12 months we can have 8 months of 56 sols and 4 of 55 Sols. This allows us to keep our 12 month division of the year(so useful due to its multiple divisors), and maintain an association between the month and a least one of the Martian moons, though to avoid confusion with the Earth month, maybe we should call it a deim.( Thus we would have 12 deims of either 55 or 56 sols to a Martian year

This now brings up the week. If we keep the normal 7 day week, then 8 of our months will have exactly 8 weeks, which is convenient.

However, just for fun, let's get a little inventive and go back to our own week's roots.
The week is based on the 7 ancient "planets": Sun, Moon, Mercury, Venus, Jupiter, and Saturn. We can still see this in some of the names,(SUNday, MO(O)Nday, SATUR(N)day). For the ones where this is not as clear, it is because the nordic equivalents were used (Thor's day became Thursday and Tyr's(Tuis') day became Tuesday, etc.)

If we maintain this tradition, we would add two days to the Martian week: Phoboday and Deimoday. In addition, just like the Earth is not represented in the Earth week, Mars would not be so in the Martian week, and would be replaced by a day representing the Earth. Since Tyr(Tuis) is the Nordic equivalent of Mars, we would lose Tuesday and gain Terraday. This would give us a week of:

Sunday, Monday, Terraday, Wednesday, Thursday, Friday, Saturday, Phoboday and Deimoday.

We'd have 74 weeks to a year vs. 95 for a 7 day week. One advantage is that the new Martian month is evenly divisible by 3. If you go to a 6 day "work week" with a three day "weekend", a business that runs full-time go go to a system where on any 3 day period 2/3 of their staff is working and the other 1/3 are off.

Now let's get back to that 0.6 sol difference between the Martian year and a whole number of Sols.

Obviously, some type of leap year system will have to be put into place. If we add a leap day every even year, we take care of 0.5 of that difference and if we make every 10 years a 2 leap day year, we take care of the remaining 0.1 day.

Of course, it isn't an exact 0.6 sol difference, so every 1600 years you drop a leap day. Then it is just a matter of adding a leap day every few thousand years as needed.

15. ### Electro522Registered Senior Member

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Wow Janus. NASA should keep that and use it for whenever humans colonize Mars. However, no one has yet to figure out the clock. How about this: in the books Red Mars, Green Mars, and Blue Mars (a series about colonizing Mars, all done by Kim Stanley Robinson), the colonists have simply made it to where all the clocks on the planet stop at midnight for the extra time of the Martian day. However, it seems like this simple system would need to be reset every few years or so, due to natural human error. So, I think we would need to either develop a brand new martian clock, or a martian "daylight savings time." Only thing is, how would we do either?

16. ### Janus58Valued Senior Member

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I think the logical approach would be to just adjust the clocks to run a bit slower. The difference only works to about 3%. This means the second, minute and hour would be a bit longer on Mars. No one would notice the difference. Of course, you aren't going to want to change a whole bunch of scientific unit, so you would restrict this to civil or everyday common usage. When needed, you can designate civil time by using 'CT', such as in 3 hrs CT.

You are also going to need times zones, And I would suggest just numbering them(CT0, CT1, CT2...). CT0 would take the role that GMT does on Earth and could alternatively be called "Mars Mean Time" (MMT).

MMT would most likely be used when coordinating between Earth and Mars time. For instance: "Departure from Earth orbit will be at 14:00 GMT March 5, 2150 and arrival to Mars orbit will be at 02:35 MMT, August 42, 37. (here I'll assume that we have adopted a Martian calendar, and the dating of the Martian year starts at the establishment of the colony.

The time zones could strictly follow meridians as we shouldn't have to worry about accommodating any political borders, though one meridian poses a interesting situation.

The meridian of which I speak is that which fulfills the role of International Date Line here on Earth. On Earth we have conveniently placed it in the Ocean (jogging it when needed to avoid land.), but we don't have this option on Mars. Wherever we put it, it will be on dry land. This would afford one the opportunity of standing with one foot in today and the other in 'yesterday' (or tomorrow depending how you look at it)

One could imagine a settlement something like some of the "twin cities" that we have on Earth that are divided by a river or other boundary. These Twin cities however would be divided by date, with it being Monday in one city and Terraday in the other.
The only real reason to do this that I can see would be as a tourist attraction though, and until tourism becomes economically feasible on Mars, I don't see this happening.

I also don't really think that we'll bring the practice of daylight savings time with us either as I don't think that it will serve much purpose there.

17. ### XyleneValued Senior Member

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1,398
Even more so in enclosed public spaces like shopping malls, cinemas, et. al.

But seriously, I'm thinking along the lines of getting the calendar to match the Martian seasons more closely, so that the months would have variable length.

For instance, here's the comparison of season length on Earth and Mars respectively;

Earth Spring 93 days/154 days Mars
" Summer 93 " /178 " "
" Autumn 90 " /142 " "
" Winter 89 " /154 " "

So we could adapt the length of the months to better coincide with the seasons.

Last edited: Apr 6, 2012