Week Lengths

The Earthian Calendar maintains the traditional 7-day week.

There are few options when it comes to the length of the week. The 7-day week has been around since the time of the Babylonians, when it was a convenient period of time between market days approximately equal to the period between phases of the moon. Since one quarter of a lunation is 29.53 days ÷ 4 = 7.38 days, this led to a constant week length of 7 days.

The 7-day week also features in Genesis (the first book of the Torah and the Bible), which describes how God created the universe in 7 days. This has led to its veneration and preservation by Jewish and Christian cultures. The Roman Empire used 8-day weeks, but converted to 7-day weeks as the Christian religion grew. The 7-day week continued to spread across the globe, and is now used practically everywhere on Earth.

There have been a few unsuccessful attempts to vary the 7-day week. For example, the French Republican Calendar, in use for about 12 years, had 10-day weeks. However these were eventually abolished because (a) workers got less rest - 1 day in every 10 instead of 1 in every 7; and (b) because it was out of synch with market days and other social cycles that stubbornly adhered to the traditional 7-day pattern.

Even when the Julian Calendar was replaced by the Gregorian and 10 days were deleted from October 1582, the 7-day cycle just kept rolling along as if nothing had happened.

A 7-day week may seem less than ideal in some ways. For example, a week with an even number of days could be evenly divided by 2, and would lend itself to alternating patterns of, for example, exercise and rest days. A 10-day week would permit decimal notation. And a pattern of 7 and 8-day weeks can be used to create a perpetual calendar.

However, the 7-day cycle is one of the only things that the entire planet Earth agrees on, and thus it would be foolish, not to mention rather pointless, to mess with it. If any new calendar introduced weeks that did not conform to the traditional 7-day pattern then several major religions, and in fact most of the planet, would immediately dismiss it as a mere curiousity, which would sort of defeat the purpose. After all, it was for this exact reason that the World Calendar was not adopted by the UN in 1955.


Names for Days of the Week

The days of the week are named for the 7 Solar System bodies visible to the naked eye: the Sun, Luna, Mars, Mercury, Jupiter, Venus and Saturn, a naming scheme in harmony with the names currently used in most languages, and with the astronomical theme of the calendar. This naming pattern was originally developed by Persian astrologers, and spread throughout the world to the point where most cultures outside of eastern Asia name their days of the week this way (see this table).

In days of olde, heavenly bodies were considered equivalent with gods. While the Persians may have named a day for Mars the planet, to the Romans and other pagan cultures the day was named in honour of Mars, the god of agriculture, war and chocolate. Thus, in merry England, some days of the week eventually became named, not for planets, but for the equivalent Germanic gods: Tiw, Woden, Thor and Freya (more about the English names for days of the week).

However, these names are not relevant to most modern humans. There are very few followers of Tiw these days, yet there are a great many people interested in Mars. So the Earthian Calendar introduces a modern set of names for days of the week based on these 7 Solar System bodies. They conform closely to those in Latin.

Earthian day name Named for Latin day name English day name Comes from
Sunday The Sun dies Solis Sunday Sun's day
Lunaday The Moon (Luna) dies Lunae Monday Moon's day
Marsday Mars dies Martis Tuesday Tiw's day
Mercuryday Mercury dies Mercurĭi Wednesday Woden's day
Jupiterday Jupiter dies Jovis Thursday Thor's day
Venusday Venus dies Venĕris Friday Freya's day
Saturnday Saturn dies Saturni Saturday Saturn's day

The name "Luna" for the Moon has been used in the Earthian days of the week, because this is the name for the Moon in many non-English languages, and is also often used in English. Personally, I prefer it. Many planets have moons, and, in my opinion, calling our moon "the Moon" is sort of like calling your dog "the Dog" instead of giving it a proper name. "Lunaday" corresponds to names for Monday in romance languages such as French and Italian: for example "Lundi" (French), "Lunedi" (Italian), etc.

To match this, I initially used "Sol" instead of "Sun", however, "Solday" simply doesn't sounds as nice and "sunny" as "Sunday".

Note: I consider these names to be an entirely optional element of the calendar. Names for days of the week are firmly ingrained in our languages, and hard to change, especially since the weeks themselves haven't changed and the names refer to the same days. Also, I wouldn't want "T.G.I. Friday's" to have to update all their marketing. Different countries that adopt the Earthian Calendar will probably just use the same names for days of the week that they do now, which is just fine.

On the other hand, the names of months in the Earthian Calendar should be changed, because they refer to different times of the year; they do not line up with any existing months.


First Day of the Week

The International Standards Organisation standard ISO8601 specifies that weeks begin with Monday. However, this would appear to be either a European and/or business-oriented bias, since it is much more traditional to start the week with Sunday. In most world cultures, Sunday has been the first day of the week for thousands of years. Also, almost all computer languages enumerate the days of the week starting from Sunday.

The concept of beginning the week with Monday, on the other hand, is a relatively recent phenomenon that has emerged as a result of increasing dominance of world culture by business, and also because most people (especially in western society) now take 2 days rest per week instead of 1. Because the 2 days rest are thought of as the "weekend", and the start of the work week is experienced emotionally and economically as the beginning of the week, we have come to think of the week as starting on Monday.

In the Earthian Calendar, weeks begin on Sunday. This choice has been made for several reasons:

  1. To conform with the long-standing traditional pattern rather than the recent phenomenon.
  2. To preserve the definition of the Sabbath from the Ten Commandments.

The Sabbath and the Weekend

This is not a religious calendar. However, Earth is home to many religious people, whom I am hoping will like this calendar. Hence, it is necessary to understand where the Sabbath and the weekend originally came from.

The Sabbath, a weekly day of rest, comes from Jewish tradition and corresponds to Saturday in English. This is reflected in the names for Saturday in several languages: e.g. "yom Shabbat" in Hebrew, "Sávato" in Greek, "Sábado" in Spanish and Portuguese, and "Sabato" in Italian. The Sabbath day is the last day of the week and allocated as a day of rest after 6 days of work.

The original definition comes from the Ten Commandments, which were reportedly given to Moses by God as a basic set of laws for the Jewish people. The importance of the Sabbath, and its purpose, are described in the fourth commandment (Exodus 20:8-11, Deuteronomy 5:12-15):

Remember the Sabbath day and keep it holy.

For six days you shall labour and do all your work.

But the seventh day is a Sabbath to the Lord your God; you shall not do any work—you, your son or your daughter, your male or female slave, your livestock, or the alien resident in your towns.

For in six days the Lord made heaven and earth, the sea, and all that is in them, but rested the seventh day; therefore the Lord blessed the Sabbath day and consecrated it.

So this scripture makes it quite clear that "the seventh day is a Sabbath", meaning that the week ends on Saturday, and therefore begins on Sunday.

Sunday was called "the Lord's Day" by the Roman Catholic Church, because it was on this day that Jesus supposedly rose from the dead. Thus, Sunday was allocated for communal worship, and so began the 2-day weekend. Hooray!

If the Earthian Calendar specified that Lunaday (Monday) was the first day of the week then a large section of the international religious community would ignore it and simply adhere to the millenia-old traditional pattern of ending the week on Saturday. It would be a major barrier to adoption of the calendar in these cultures. By beginning the week with Sunday, these cultures are much more likely to accept the calendar because it won't conflict with their beliefs. Although the business culture may view the week as beginning on a Monday, clearly their feelings about this are not as strong, since many businesses still use calendars with Sunday as the first day of the week with no fuss whatsoever.

As a science writer and not a theologian, it is not my intention to assert that the Ten Commandments are strictly relevant to modern society (although, frankly I think modern society would be considerably better off if they were). The point here is that we have this rather popular 3300-year-old teaching clearly describing the Sabbath, which gave us the weekend that we know and love to this day. There are no religious or scientific reasons to conflict with this, and since we already observe the Sabbath (many without realising it) and most people are already quite used to starting the week on Sunday, there seems little reason to change it. It is a mystery why ISO thought they should.


Numbers for Days of the Week

The days of the week are numbered from 1-7. Since days of the month and months of the year are numbered from 1, it's consistent and logical to number days of the week from 1 also. Numbering the days from 1-7 is the same as in ISO8601, but because weeks in the Earthian Calendar begin with Sunday, the numbers correspond to different days. The differences are shown in the table below.

While the days of the week in most languages are named for the planets (or corresponding gods), some number them. These are shown for comparison, along with the numbering convention in several popular computer languages. Note that ISO8601 is the only system that assigns the number 7 to Sunday.

Earthian Day Name Earthian Calendar English Day Name ISO8601 Hebrew, Arabic, Portugeuse, Greek, Kazakh, Persian, Vietnamese Eastern European, Chinese, Mongolian .NET, Java, PHP, JavaScript
Sunday 1 Sunday 7 1 none 0
Lunaday 2 Monday 1 2 1 1
Marsday 3 Tuesday 2 3 2 2
Mercuryday 4 Wednesday 3 4 3 3
Jupiterday 5 Thursday 4 5 4 4
Venusday 6 Friday 5 6 5 5
Saturnday 7 Saturday 6 7 6 6


Week Numbers

Week within a year are numbered from 1-52 or 53.

In ISO8601, week 1 of a year is defined as being the first week with 4 or more days in that year. In other words, a week is counted as belonging to the year that contains most of its days.

This is fairly logical, so the same rule is used in the Earthian Calendar.

The table below illustrates week numbering around New Year's Day for the next few years. If the year begins on a Sunday, Lunaday, Marsday or Mercuryday (as in year 0003..0006), then New Year's Day will be in week 1 of the new year. However, if the year begins on Jupiterday, Venusday or Saturnday (as in year 0001, 0002, 0007 and 0008), then New Year's Day will be in the last week of the previous year.

Sunday Lunaday Marsday Mercuryday Jupiterday Venusday Saturnday Week of Year
0000 Pisces 27 0000 Pisces 28 0000 Pisces 29 0000 Pisces 30 0001 Aries 1 0001 Aries 2 0001 Aries 3 Week 53 of 0000
0001 Pisces 26 0001 Pisces 27 0001 Pisces 28 0001 Pisces 29 0001 Pisces 30 0002 Aries 1 0002 Aries 2 Week 52 of 0001
0003 Aries 1 0003 Aries 2 0003 Aries 3 0003 Aries 4 0003 Aries 5 0003 Aries 6 0003 Aries 7 Week 1 of 0003
0003 Pisces 30 0004 Aries 1 0004 Aries 2 0004 Aries 3 0004 Aries 4 0004 Aries 5 0004 Aries 6 Week 1 of 0004
0004 Pisces 29 0004 Pisces 30 0005 Aries 1 0005 Aries 2 0005 Aries 3 0005 Aries 4 0005 Aries 5 Week 1 of 0005
0005 Pisces 28 0005 Pisces 29 0005 Pisces 30 0006 Aries 1 0006 Aries 2 0006 Aries 3 0006 Aries 4 Week 1 of 0006
0006 Pisces 27 0006 Pisces 28 0006 Pisces 29 0006 Pisces 30 0006 Pisces 31 0007 Aries 1 0007 Aries 2 Week 53 of 0006
0007 Pisces 25 0007 Pisces 26 0007 Pisces 27 0007 Pisces 28 0007 Pisces 29 0007 Pisces 30 0008 Aries 1 Week 52 of 0007