The Fortieth of July

Copyright © 1997 by Pierre Hallet

One evening at a party, I happened to be cornered by a youngster who claimed he had bought all of my essay collections. He said this was a most uncommon feat and I had to concur. (Of course, I encourage heartily any Gentle Reader who would feel himself challenged to try to duplicate this youngster's exploit.)

Anyway, his readings had inspired in him a number of not-too-serious riddles that he began to throw at me. I can remember distinctly the following one, "Suppose that after men have a station on the Moon, they establish another one on the Sun. Which time would they have on their watches?" His answer was "always noon, because the Sun is constantly at its brightest." But I fooled him there - MY answer was "always midnight, since the Sun is constantly underfoot."

More seriously now, this 'riddle' reminded me of a circumstance when I was asked by another reader to comment about a detail in a famous SF book he had just read. Here also the subject was time measurement, but on Mars. I had never seriously considered the subject, so his question led me to a number of speculations - and as you have already guessed, I am now going to let you share in them.

Some of you Gentle Readers - say the ones in their late youth - will remember the time, back in the fabulous fifties, when Alfred Bester wrote that best-seller of his called The Demolished Man. The story is set in 2301 AD, and of course the author enlivens the scene by giving a number of details on daily life in the 24th century. Thus on the second page, the main character (called Ben Reich - remember?) glances at a clock giving "the time panorama of the solar system." The dials read "February 15, 0205 Greenwich" for Earth (nothing special in that) and "Duodecember 35, 2220 Central Syrtis" for Mars.

Of course, the reading for Mars was what prompted my reader - but not all of it, of course. He shrugged away the Central Syrtis bit as a sort of cliché. And he wasn't puzzled by the hour difference between the Earth and Mars. After all, time zones are a well-accepted fact of life in these United States, so why not between planets? No, he was struck by the exotic month and the unusual day of month. His reaction was plainly, "Why wouldn't people on Mars use the same calendar as anyone else?"

Ah, but even down here on Earth NOT anyone else is using the same calendar as the one most of you are familiar with. Right in the United States, Jewish people have a calendar of their own, with years of 12 or 13 'lunar months' of 29 or 30 days. Agreed, they use it mostly for religious purposes, and go back to the good old Gregorian calendar for daily life. In other parts of the world, however, Moslems have a calendar of 12 lunar months of 29 or 30 days, and although their year has then only 354 or 355 days, and so is out of pace with seasons, they insist on using it for their daily life as well. I will not go too deeply into details on other calendars, which I have given elsewhere. (See "The Days of Our Years" in Of Time, Space and Other Things).

Now suppose that we set up manned outposts on other planets (or, for that matter, satellites) in the solar system. How would people there count time?

Obviously, the simplest way would be for them to keep some Earth time, say Greenwich time, and let go at that. Surely this would make relationships with Earth easier. If you decide that radio contact is to begin at 09:30 each day, it sure helps to agree on what '09:30' means. Just think back of the early 19th century, when each place had its own separate hour, with 'noon' being the moment the Sun was highest on that place - an awkward situation, but one you could live with in those pre-industrial days. But when you force on this peaceful world that fast-moving means of transportation, the railroad, to make THIS practical you have to have a railroad schedule. And to make THAT work, you just have to match clocks between stations. Synchronizing the time in a whole area makes life simpler for the travelers without too much trouble for the non-travelers, who must change their clocks just once for all time- and by a small amount at that.

Now the Earth system of time is based on astronomical factors on which our whole daily life depends. The alternation of day and night is the most unmistakable factor, and at least all calendars on Earth agree more or less on what a day is - and even on the number of days to make a week, although this is much less natural. Beyond that, the cycle of the phases of the Moon defines a 'lunar month' of some 29½ days, while the cycle of the seasons defines a 'solar year' of some 365¼ days, and these round out the astronomical factors which have shaped our various calendars. And speaking of 'daily life', it is obvious that evolution has adapted our bodies to the 24-hour day, so that we could not live a long period on another cycle without endangering our health. Biologists proved this by using artificial light to force mice to live unusual cycles, say of 36-hour days, and found life spans were reduced. We might someday find drugs to bypass this limitation, but let us play it safe and not count on this for the foreseeable future.

Thus our way of counting time is not arbitrary, but closely related to the 'local conditions' - a glance at a clock and/or a calendar gives you a good idea of whether it is clear or dark outside, or whether it is warm or cold, or whether you should sow or reap.

Let us go back to our manned stations on other planets. Using some Earth time has some advantages, but this time is totally disconnected from the local conditions. You might say, "Who cares?", and you might very well be right. If the station is, say deeply buried in the ground, to get some protection from the cold or from falling meteorites, then its inhabitants would not even be aware of the 'local' conditions, and might very well choose any convenient way to measure time. In most cases, using local time would be excluded from the start, because it would not be possible to adapt oneself to the day-and-night cycle. On the Moon, for example, the 'day' lasts about one Earth month (no, it is NOT a coincidence), and I am pretty sure that no one would care to stay awake for 500 hours and to sleep the next 200 hours. Would you?

Ah, but what of Mars? Mars has an atmosphere, and although it is thin and unbreathable, it might give enough protection against meteorites to make burying the station unnecessary. In this case, the local conditions would be a daily concern of the Martian colonists. Mars has seasons, which might have a significant impact, say on the feasibility of travelling from one station to the next. And finally, the duration of the day-and-night cycle on Mars is almost equal to ours, so unlike the Moon, this cycle will actually be useful to humans.

One might then very well argue that future settlements on Mars will not be buried, but just be covered with domes, in order to use the daylight. Or at least they might be that way around 2301 AD. And then, inevitably, one would think of the impact on time measurement.

Let us begin with the hour. Almost any SF reader knows that a day on Mars lasts, in Earth units, about 24 hours 37 minutes. I must warn you here that we will have to change slightly this value later - but let us stick to it for the time being. So what do the Martian settlers do?

If they just use an ordinary watch synchronous with Earth movements, it will hopelessly lag behind the Sun. If one day it reads noon in the middle of the day, then two weeks later it will read noon at dawn. Now a solution of sorts would be to move the watch back 37 minutes each day, say at noon, but would YOU like it? I know I wouldn't, and settlers wouldn't either. They would keep forgetting it, so the watches would have to be built to adapt themselves automatically. But does this really solve the problem? With that trick, each time between 12:00 and 12:37 PM happens twice in succession. So you plan to catch the 12:24 from Syrtis? Which one, the 12:24 'before', or the 12:24 'after'? And how easy is it to boil eggs between 12:36 and 12:02?

Inevitably, Martian settlers would eventually use watches running a trifle differently from Earth watches, in fact about 2½ % slower, so that they would run at the Martian pace of day and night. Why not call them 'slow watches'? Also, this opens a new field for practical jokes, such as offering fast watches on Mars or slow watches on Earth. And as we speak of 'short tons' and 'long tons', Martians settlers might speak of 'long hours' or 'short hours'. There might be an attempt to give new names to Martian units, but I suspect that they are too close to their Earth counterparts for the attempt to succeed.

Does this settle the matter of hours? As a scientist, I guess that lots of people would be annoyed by that 'long hour' setup. You see, our second - the short second - is not just a bit of time, but also a basic unit for all kinds of measurements. For example, you determine the radioactivity of a sample by measuring how much it radiates in a given amount of time, say in one second... Got it? Either scores of data and tables would have to be 'translated' in terms of long seconds, or, more probably, scientists would go on using the short second for their work, while otherwise using the long second like everyone else. After all, in our 20th century, US scientists are using meters and kilograms in the lab and inches and ounces at home, and they can make the switch without damaging their sanity - or so it seems.

So, let us suppose that everyone on Mars wears a slow watch. The day and night are cared for. Next, everyone agrees to have seven-day weeks. But what makes a month? On Earth, the month was originally a way of counting long spans of days from the phases of the Moon, in times when there was precious little arithmetic around to count them otherwise. Now we are sophisticated enough to have better means, and for that matter Mars has two moons, Phobos and Deimos, and keeping track of both their phases is liable to give more headache than help. So why not skip the months altogether and just use days and years?

Maybe so, but I find it unlikely. Some 20th-century computers DO use what is rather oddly called a 'Julian date' (actually, this is a misnomer, but I won't pick nits here since I have already done so in another essay), made of the year plus the number of the day within the year - thus, '97364' is the 364th day of 1997, or December 30. No one but computers likes that. You might say that the dislike comes from the need to translate over and over to and from our day-and-month scheme. Surely if everyone used Julian dates, no one would object to using them? Perhaps, but isn't it a bit late to think of that? And are you sure there is enough room on your wall for this long, long calendar?

So say we want to divide somehow our 'year' into months. To get any further, we must know how many days there are in a Martian year. Now if we wish to be accurate, the problem is less trivial than it appears. Here some readers might disagree, grab an almanac, find that Mars completes a turn around the Sun in about 687 days, and shrug, "So what? The answer is there, plainly written." Ah, but almanacs are made for us Earthlings and give their data in EARTH-days. Now we all agree that any true-blooded Martian settler has no use for Earth-days. OK, so why not compute how much this 687-day year makes in 'long days' of 24 hours 37 minutes? Then the answer is slightly more than 669 days. Better... but still slightly wrong.

Indeed, if you look carefully at your almanac, you will find, next to the 24 hours 37 minutes 23 seconds for Mars, a duration of 23 hours 56 minutes 4 seconds for the Earth, instead of the round 24 hours you might have expected. This is because the tables give the 'sidereal day' - the period of rotation as seen from infinity, or at least from distant stars - rather than the 'solar day' - the period of rotation as seen from the Sun. Once again, I will not give details here as I gave them at some other place (See "Round and Round and..." in Of Time, Space and Other Things), but the figures for the Earth show plainly that the solar day is the one to be used.

The computation is straightforward, but I am afraid you will find it rather boring, so I will go directly to the results : computing from values (in Earth-day units) of 686.98 for the Martian sidereal year and 1.02596 for the Martian sidereal day, we obtain a Martian solar day of 1.02750 Earth-day, or 24 hours 39 minutes 36 seconds - so that the year comes out at about 668.6 solar days.

Before I am drowned under letters from irate readers, let me specify that I should also have taken into account a slight difference between the 'sidereal year' given by the almanac and the 'tropical year' which defines seasons. I chose to drop it because the effect is so small that its impact is limited to the first unwritten decimal of the last figure we have obtained.

Thus a Martian year is to be divided into 668 or 669 days. Comparing the value 668.6 to its Earth counterpart of 365¼ implies that on Mars about three years out of five would be leap years instead of one out of four on Earth. In other words, a leap year would be the rule instead of the exception. But let us concentrate now on how to split such awkward numbers of days into months? Here I can imagine two competing groups with contradictory ideas.

One group would insist on months with thirty or thirty-one days, to make months have 'the right size'. Their year would have 22 months, and depending on to the year, 13 or 14 of them would be 30-day months, and the remaining nine or eight would be 31-day months.

The other group would insist on a year of twelve months, to make months be 'the right number'. They would emphasize that a 22-month year cannot be divided into quarters, and counter with a familiar 12-month year, with three or four 55-day months and nine or eight 56-day months.

This quarrel might end with a compromise, say 16 months of 41 or 42 days. Now only such a compromise would allow us the delight of BOTH an unusual number of months AND an unusual number of days within the month.

But how would these months be called? If the 12-month year wins, we may take for granted that these months would have the same names as the months on Earth. It would just be too convenient. And even in the case where the year would have just a few more months than ours, I guess that the first twelve would have the usual names, with extra names added at the end. But then, which names?

If we turn to the ancient Romans to see how they named OUR months, we discover that they found month-naming a boring business indeed. They managed for a few centuries without even naming two months - the future January and February - since nothing important happened in mid-winter anyway, so why bother? And among the remaining months that the Romans made an effort to name, only the first four (March, April, May and June) got names requiring a bit of poetry or imagination. The next two were 'Quintilis' and 'Sextilis', which was just a funny way of saying 'fifth' and 'sixth'. (As you know, they happened to be renamed later 'July' and 'August', to honor Julius Caesar and the emperor Augustus.) Finally, the next four months were simply called by the Latin names for the figures seven to ten, with the suffix 'bris' appended to them - namely Septembris, Octobris, Novembris and Decembris. In the centuries that followed, the two anonymous months at the end of the year finally got names, and the beginning of the year was moved so that they came first. (This ought to have changed the names of the last four months - after all, September was not the seventh month any more but now the ninth one, and so it should have been renamed November, and so on, but I guess that everybody shuddered at the thought of the confusion that might have ensued.)

However, the Roman way gives us a clue - the names of the last months form a TREND, and we can follow this trend. This would not be the first time that a trend is used in naming - the first two chemical elements to be synthesized beyond uranium were named 'neptunium' and 'plutonium' because the planets Neptune and Pluto come beyond Uranus in the solar system. If 'December' is 'the Latin for ten', plus 'ber', the following month would be 'the Latin for eleven' plus 'ber'. The result would be 'Undecimber', but this unlikely 'i' would be replaced by an 'e', so that the final name would be 'Undecember'. And what about the next one? Well... 'Duodecember', of course. For the record, these two names WERE used once in the history, during the famed 'Confusion Year' (46 BC), a ghastly (but exceptional) year of 445 days designed by Julius Caesar to set the calendar right ever after... but let us not digress here.

Anyway, here we are! The "Duodecember 35" of Bester's book would be a day in the fourteenth month of a Martian year containing at most twenty months (otherwise, months couldn't be 35 days long). What would be the names of the other months? Following the trend, we get 'Tredecember', then the rather unpalatable 'Quatuordecember'... Should I go further? These names may have an exotic taste, but I find them just too spicy and confusing for daily life. I suspect that the Martian colonists would settle for a 12-month year, just to feel comfortable. The price of having 56-day months would be light compared with the awkward names of months-to-be.

Have we settled the matter? Well... There is the subject of holidays. For example, suppose that you are colonists from the United States. Then, when do you celebrate the Fourth of July? At the same time as the Earth's Fourth of July, or on YOUR Fourth of July? A way to elude the problem is to think that Martians will have their own holidays based on important dates of Martian history. After all, the Americans have their Fourth of July, but the French have their Fourteenth of July. Would it not be appropriate if the Martians had their Fortieth of July?

Or what about Christmas? This is related to an anniversary on Earth. If you wish to celebrate it at the same time as on Earth, you must be prepared foro the idea of a Christmas in March, or July, or October - but if on the contrary you choose to celebrate it on your own December 25, then you might have to expect a four-week delay between Christmas and New Year's Eve - if the latter occurs on December 55.

And speaking of birthdays, suppose your baby girl is born on Mars, say on the 43rd of May. When will you celebrate her first birthday? Well, obviously on the next 43rd of May. Ah, but almost two Earth-years have passed, and this child of one will walk, and probably talk as well. And as 'years' pass by, your daughter will go to grammar school at three, menstruate at seven, marry at eleven. And if she turns fifty, this will be uncommon enough for the mayor to come and congratulate her at her nursing home. Did you notice that SF novelists never hesitate to speak of "a beautiful girl in her middle twenties" without any qualification, even if the scene is supposed to be Betelgeuse or Aldebaran? Should you ever dare to ask them "Twenty what?", they would stare blankly at you, as though years were something universal. Now on the very first planet (leaving aside the Moon, which is a satellite) on which mankind might have settlements, a woman "in her middle twenties" would very likely be a grandmother!

The subject is not exhausted, and I leave you free to wonder about how the date of Easter should be defined, how astrologers would handle 16 or 22-month years, or how Martians citizens staying on Earth for long periods would manage to celebrate their birthdays on February 39. I would like to add a last important point, namely that the number of the year itself would have to be 'Martianized'. In Bester's book, the year is 2301 AD throughout the solar system. But think : Bester's story begins on February 15, 2301, on Earth, and apparently on Mars it is Duodecember 35, ALSO 2301. Now go back a few weeks, to January 1, 2301 on Earth. Then it might be, say Undecember 33, 2301 on Mars. Go back one day and this is December 31, 2300 on Earth. Will it be Undecember 32, 2300 on Mars? Now suppose you live on Mars. Would you appreciate changing years right in the middle of just any month, just because the bums on the next planet find it convenient to them? No sir! You would have your own A.D. system - After Discovery, maybe? And let the stinking Eartheys rot with their petty years and stringy months that do not even have forty days.