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Subsections

5. The Week

The Christian, the Hebrew, and the Islamic calendars all have a 7-day week.

5.1 What is the origin of the 7-day week?

Digging into the history of the 7-day week is a very complicated matter. Authorities have very different opinions about the history of the week, and they frequently present their speculations as if they were indisputable facts. The only thing we seem to know for certain about the origin of the 7-day week is that we know nothing for certain.

The first pages of the Bible explain how God created the world in six days and rested on the seventh. This seventh day became the Jewish day of rest, the sabbath, Saturday.

Extra-biblical locations sometimes mentioned as the birthplace of the 7-day week include: Egypt, Babylon, Persia, and several others. The week was known in Rome before the advent of Christianity.

   
5.2 What do the names of the days of the week mean?

An answer to this question is necessarily closely linked to the language in question. Whereas most languages use the same names for the months (with a few Slavonic languages as notable exceptions), there is great variety in names that various languages use for the days of the week. A few examples will be given here.

Except for the sabbath, Jews simply number their week days.

A related method is partially used in Portuguese and Russian:

English Portuguese Russian Meaning of Russian name
Monday segunda-feira ponedelnik After do-nothing day
Tuesday terca-feira vtornik Second day
Wednesday quarta-feira sreda Center
Thursday quinta-feira chetverg Four
Friday sexta-feira pyatnitsa Five
Saturday sabado subbota Sabbath
Sunday domingo voskresenye Resurrection

Most Latin-based languages connect each day of the week with one of the seven ``planets'' of the ancient times: Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn. French, for example, uses:

English French ``Planet''
Monday lundi Moon
Tuesday mardi Mars
Wednesday mercredi Mercury
Thursday jeudi Jupiter
Friday vendredi Venus
Saturday samedi Saturn
Sunday dimanche (Sun)

The link with the sun has been broken in French, but Sunday was called dies solis (day of the sun) in Latin.

It is interesting to note that also some Asiatic languages (for example, Hindi, Japanese, and Korean) have a similar relationship between the week days and the planets.

English has retained the original planets in the names for Saturday, Sunday, and Monday. For the four other days, however, the names of Anglo-Saxon or Nordic gods have replaced the Roman gods that gave name to the planets. Thus, Tuesday is named after Tiw, Wednesday is named after Woden, Thursday is named after Thor, and Friday is named after Freya.

5.3 What is the system behind the planetary day names?

As we saw in the previous section, the planets have given the week days their names following this order:

Moon, Mars, Mercury, Jupiter, Venus, Saturn, Sun

Why this particular order?

One theory goes as follows: If you order the ``planets'' according to either their presumed distance from Earth (assuming the Earth to be the center of the universe) or their period of revolution around the Earth, you arrive at this order:

Moon, Mercury, Venus, Sun, Mars, Jupiter, Saturn

Now, assign (in reverse order) these planets to the hours of the day:

1=Saturn, 2=Jupiter, 3=Mars, 4=Sun, 5=Venus, 6=Mercury, 7=Moon, 8=Saturn, 9=Jupiter, etc., 23=Jupiter, 24=Mars

Then next day will then continue where the old day left off:

1=Sun, 2=Venus, etc., 23=Venus, 24=Mercury

And the next day will go

1=Moon, 2=Saturn, etc.

If you look at the planet assigned to the first hour of each day, you will note that the planets come in this order:

Saturn, Sun, Moon, Mars, Mercury, Jupiter, Venus

This is exactly the order of the associated week days.

Coincidence? Maybe.

5.4 Has the 7-day week cycle ever been interrupted?

There is no record of the 7-day week cycle ever having been broken. Calendar changes and reform have never interrupted the 7-day cycles. It very likely that the week cycles have run uninterrupted at least since the days of Moses (c. 1400 BC), possibly even longer.

Some sources claim that the ancient Jews used a calendar in which an extra Sabbath was occasionally introduced. But this is probably not true.

5.5 Which day is the day of rest?

For the Jews, the Sabbath (Saturday) is the day of rest and worship. On this day God rested after creating the world.

Most Christians have made Sunday their day of rest and worship, because Jesus rose from the dead on a Sunday.

Muslims use Friday as their day of rest and worship. The Qur'an calls Friday a holy day, the ``king of days''.

   
5.6 What is the first day of the week?

The Bible clearly makes Saturday (the Sabbath) the last day of the week. Therefore it is common Jewish and Christian practice to regard Sunday as the first day of the week (as is also evident from the Portuguese names for the week days mentioned in section 5.2). However, the fact that, for example, Russian uses the name ``second day'' for Tuesday, indicates that some nations regard Monday as the first day.

In international standard IS-8601 the International Organization for Standardization (ISO) has decreed that Monday shall be the first day of the week.

5.7 What is the week number?

International standard IS-8601 (mentioned in section 5.6) assigns a number to each week of the year. A week that lies partly in one year and partly in another is assigned a number in the year in which most of its days lie. This means that Week 1 of any year is the week that contains 4 January,

or equivalently

Week 1 of any year is the week that contains the first Thursday in January.

Most years have 52 weeks, but years that start on a Thursday and leap years that start on a Wednesday have 53 weeks.

5.8 How can I calculate the week number?

If you know the date, how do you calculate the corresponding week number (as defined in IS-8601)?

1.
Using the formulas in section 2.15.1 calculate the Julian Day Number for today (Jt) and for 1 January of the current year (Jb).

2.
Calculate:

\begin{displaymath}\begin{array}{rl}
d & = (J_b + 3) \bmod 7 \\
w & = (J_t + d - J_b + 4)/7
\end{array} \end{displaymath}

(The division is an integer division in which the remainder is discarded.)

3.
We now have to distinguish between a few cases:
a)
If w lies in the range 1 to 52, w is the week number.

b)
If w=53 and d=6, w is the week number.

c)
If w=53 and d=5 and the current year is a leap year, w is the week number.

d)
If w=53 and d does not meet the conditions mentioned in b) and c) above, the day belongs to week 1 of the following year.

e)
If w=0, the day belongs to the last week of the previous year. In this case you must repeat the calculations in step 2, but setting Jb to the Julian Day Number of 1 January of the previous year.

[There must be ways to simplify this calculation. Please write to me if you have a better algorithm.]

5.9 Do weeks of different lengths exist?

If you define a ``week'' as a 7-day period, obviously the answer is no. But if you define a ``week'' as a named interval that is greater than a day and smaller than a month, the answer is yes.

The French Revolutionary calendar used a 10-day ``week'' (see section 6.1).

The Maya calendar uses a 13 and a 20-day ``week'' (see section 7.2).

The Soviet Union has used both a 5-day and a 6-day week. In 1929-30 the USSR gradually introduced a 5-day week. Every worker had one day off every week, but there was no fixed day of rest. On 1 September 1931 this was replaced by a 6-day week with a fixed day of rest, falling on the 6th, 12th, 18th, 24th, and 30th day of each month (1 March was used instead of the 30th day of February, and the last day of months with 31 days was considered an extra working day outside the normal 6-day week cycle). A return to the normal 7-day week was decreed on 26 June 1940.


next up previous contents
Next: 6. The French Revolutionary Up: Frequently Asked Questions about Previous: 4. The Islamic Calendar
Claus Tøndering - claus@tondering.dk
Используются технологии uCoz