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JohnD
2014-May-11, 10:21 AM
A friend just sent me a chain letter email, pointing out that this year will see 5 Fridays, Saturday and Sundays, just in the month of August. This is said to recur only every 823 years. No, I haven't checked the calendar for this year or the next millenium to see if this is true, because the rider to the email is that Chinese tradition says that this is most propitious, but only if you tell someone else, so pass it on. The usual chain mail nonsense.

But then I thought - do the Chinese really use a seven day week? And according to Internet sources, they do, and so do the Japanese. When those and the Western cultures have developed so independently, why have they both chosen a seven day week? After all, the week could be as little as 5 to 12 or more days long, and a five day week provides exactly 73 weeks in the year, a far more convenient fraction.

Why seven days?
JOhn

Noclevername
2014-May-11, 11:00 AM
My wild guess-- Lunar cycles? If you count four phases of the Moon, that's one every 7 days.

profloater
2014-May-11, 12:00 PM
I would also guess moons as being the most obvious cosmic timer after days. It took a long time , I venture, to work out years as opposed to seasons, so after moons it would be winters and so on. The moon has its four phases, so that would give you seven day weeks.

grapes
2014-May-11, 01:42 PM
Gotta be the moon :)

Trebuchet
2014-May-11, 02:28 PM
The Chinese, and everyone else, use a common calendar, all over the world. Yes, there are religious calendars in use but for general business, the Gregorian calendar is universal.

Wikipedia (http://en.wikipedia.org/wiki/Week) has some history with other weeks.

Hornblower
2014-May-11, 05:57 PM
A friend just sent me a chain letter email, pointing out that this year will see 5 Fridays, Saturday and Sundays, just in the month of August. This is said to recur only every 823 years. No, I haven't checked the calendar for this year or the next millenium to see if this is true, because the rider to the email is that Chinese tradition says that this is most propitious, but only if you tell someone else, so pass it on. The usual chain mail nonsense.

But then I thought - do the Chinese really use a seven day week? And according to Internet sources, they do, and so do the Japanese. When those and the Western cultures have developed so independently, why have they both chosen a seven day week? After all, the week could be as little as 5 to 12 or more days long, and a five day week provides exactly 73 weeks in the year, a far more convenient fraction.

Why seven days?
JOhn
My bold. Whoever said that must not have looked at a calendar very closely. That will happen any time a 31-day month starts on a Friday. Most years have at least one, with some having two. In regular years if January starts on Friday, so will October. In leap years it its January and July. Only in years in which June 1 is a Friday are there no 31-day months starting on Friday. If we limit it to August, then it will recur after 5, 6 or 11 years, depending on where the leap years fall.

Jens
2014-May-12, 01:02 AM
My understanding is that they did not develop independently, but rather from a common calendar developed perhaps by the Sumerians.

Noclevername
2014-May-12, 01:46 AM
My understanding is that they did not develop independently, but rather from a common calendar developed perhaps by the Sumerians.

IIRC the original days were named after the known heavenly bodies; the Sun, Moon and visible planets. We still use Sunday, Moon-day, and Saturn-day.

Jens
2014-May-12, 07:59 AM
Yes, and in French mardi, mercredi and vendredi as well.

Strange
2014-May-12, 09:14 AM
Aren't the days just called 1, 2, 3 ... in Chinese? (And in some European languages(s)?)

Jens
2014-May-12, 10:05 AM
Nowadays, yes.

Strange
2014-May-12, 10:54 AM
Nowadays, yes.

Ooh! Interesting. Do you know when and why it changed? Something to do with the Communist government? Or an earlier modernisation? And were they similar to the Japanese names before (I assumed the Japanese might have got their names from China.)

Portuguese calls Monday to Friday "second holiday", "third holiday", etc. since they "pagan" names were replaced in the 6th C.

Glom
2014-May-12, 11:33 AM
The moon is key. The word month after is derived from Moon.

And the naming of days are the seven wandering celestial bodies is pretty clear in the original French.
Lundi Moon day
Mardi Mars day
Mecredi Mercury day
Jeudi Jupiter day
Vendredri Venus day
Samedi Saturn day
Dimanche er day of the English Channel

grapes
2014-May-12, 12:35 PM
The moon is key. The word month after is derived from Moon.

And the naming of days are the seven wandering celestial bodies is pretty clear in the original French.
Lundi Moon day
Mardi Mars day
Mecredi Mercury day
Jeudi Jupiter day
Vendredri Venus day
Samedi Saturn day
Dimanche er day of the English Channel
Besides the obvioius ones, in English we have
Tuesday Tiw's day (Mars)
Wednesday Odin's day (Mercury, not sure why)
Thursday Thor's day (Jupiter)
Friday Frige's day (Norse god Frige, Venus was Frige's star)

iquestor
2014-May-12, 02:03 PM
actually, Ancient Astronaut Theorists put forth the common 7 days calendar as direct evidence of alien influence on ancient cultures. :)

profloater
2014-May-12, 02:14 PM
actually, Ancient Astronaut Theorists put forth the common 7 days calendar as direct evidence of alien influence on ancient cultures. :)
Since it is well known that ancient aliens had seven fingers?

Strange
2014-May-12, 02:28 PM
Three and a half on each hand.

Trebuchet
2014-May-12, 04:20 PM
We also use ancient gods & such for the first eight months of the year. Then we hit September (the seventh month), October (the eighth month), November (the ninth month) and December (the tenth month). Because the year used to start with the Spring Equinox.

JohnD
2014-May-12, 09:16 PM
Doh!
Lunar months, of course. Thnaks to all for pointong out what I should have seen immediately.

And thanks, Hornblower, for the mythbuster. See: http://www.timeanddate.com/calendar/823-years.html
I DID say it was nonsense.

John