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The perpetual calendar



 
 
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  #21  
Old February 19th 10, 04:56 PM posted to sci.math,sci.physics,sci.astro,sci.lang,alt.usage.english
Yusuf B Gursey
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Posts: 78
Default The perpetual calendar

On Feb 19, 5:14*am, Ruud Harmsen wrote:
Fri, 19 Feb 2010 10:34:10 +0100: James Hogg :
in sci.lang:

What could be simpler?


The Jewish calendar.


the Jewish Calendar has a complicated algorithm, IIRC refined by the
famous 18th cent. mathematician Euler.
the complications are due to making sure that certain holidays do not
fall on certain days.

http://en.wikipedia.org/wiki/Hebrew_Calendar



Hebrew calendar

....

Special holiday rules
Adjustments are made to ensure certain holy days and festivals do or
do not fall on certain days of the week.

Yom Kippur
Adjustments are made to ensure that Yom Kippur, on which no work can
be done, does not fall on Friday (the day prior to the Sabbath) to
avoid having Yom Kippur's restrictions still going on at the start of
Sabbath, or on Sunday (the day after Shabbat) to avoid having the
Shabbat restrictions still going on at the start of Yom Kippur.

The Rosh Hashanah postponement rules are the mechanism used to make
the adjustments. As Yom Kippur falls on Tishrei 10, and Rosh Hashanah
falls on the 1st, the adjustment is made so that Rosh Hashanah does
not fall on a Wednesday or Friday.



To ensure that Yom Kippur does not directly precede or follow Shabbat,
and that Hoshana Rabbah is not on a Shabbat, in which case certain
ceremonies would be lost for a year, the first day of Rosh Hashanah
may only occur on Mondays, Tuesdays, Thursdays, and Saturdays (the
"four gates"). Adjustments are made to ensure that Rosh Hashanah does
not fall on the other three days. To achieve that result the year may
be made into a short (chaser) year (both Kislev and Cheshvan have 29
days) or full (maleh) year (both Kislev and Cheshvan have 30 days).
(see table)

The day of the week on which Rosh Hashanah falls in any given year
will also be the day on which Sukkot and Shmini Atzeret will occur.




--
Ruud Harmsen,http://rudhar.com



  #22  
Old February 19th 10, 04:59 PM posted to sci.math,sci.physics,sci.astro,sci.lang,alt.usage.english
António Marques[_2_]
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Posts: 32
Default The perpetual calendar

Yusuf B Gursey wrote (19-02-2010 15:35):

the Orthodox (Eastern) churches have a slightly different system.
dunno exactly what it is.


Afaik the system is the same, it's March 21 that is different.
  #23  
Old February 19th 10, 05:25 PM posted to sci.math,sci.physics,sci.astro,sci.lang,alt.usage.english
Mike Barnes
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Posts: 25
Default The perpetual calendar

John Atkinson :
Halmyre wrote:

I just wish they'd settle on a date for Easter and be done with it.

But, the whole point of Easter is that it has a full moon!


A full-*ish* moon, actually. The definitions of the equinox and full
moon used when determining Easter are rather different from the real
definitions used by astronomers, which would actually give rise to
different (perhaps several weeks different) Easter dates depending on
one's longitude.

But I thought that for most people the whole point of Easter is that
they get time off work.

--
Mike Barnes
Cheshire, England
  #24  
Old February 19th 10, 06:02 PM posted to sci.math,sci.physics,sci.astro,sci.lang,alt.usage.english
LFS
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Posts: 1
Default The perpetual calendar

Evan Kirshenbaum wrote:
"Peter T. Daniels" writes:

On Feb 19, 4:34 am, James Hogg wrote:


My Book of Common Prayer makes things easy by pointing out that
"the moon referred to in the definition of Easter Day is not the
actual moon of the heavens, but the Calendar Moon, or Moon of the
Lunar Cycle, which is counted as full on its fourteenth day,
reckoned from the day of the Calendar New Moon inclusive." Also, in
a Bissextile Year "the number of Sundays after Epiphany will be the
same, as if Easter Day had fallen one day later than it really
does."

Which is why Easter and Passover rarely coincide -- we happen to have
had a spate of coincidence in recent years, but that'll soon be over.


Which years were those? I had thought that the current Easter rules
made it impossible for it to fall on the 15th of Nissan.


I understood that it is not actually impossible but that the coincidence
is very rare. ISTR it happened at some point in the early 1980s. Of
course, Passover week quite often covers Good Friday and Easter Sunday -
it does this year.

--
Laura
(emulate St. George for email)



  #25  
Old February 19th 10, 06:06 PM posted to sci.math,sci.physics,sci.astro,sci.lang,alt.usage.english
Peter T. Daniels
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Posts: 200
Default The perpetual calendar

On Feb 19, 11:52*am, Evan Kirshenbaum wrote:
"Peter T. Daniels" writes:

On Feb 19, 4:34 am, James Hogg wrote:
My Book of Common Prayer makes things easy by pointing out that
"the moon referred to in the definition of Easter Day is not the
actual moon of the heavens, but the Calendar Moon, or Moon of the
Lunar Cycle, which is counted as full on its fourteenth day,
reckoned from the day of the Calendar New Moon inclusive." Also, in
a Bissextile Year "the number of Sundays after Epiphany will be the
same, as if Easter Day had fallen one day later than it really
does."


Which is why Easter and Passover rarely coincide -- we happen to have
had a spate of coincidence in recent years, but that'll soon be over.


Which years were those? *I had thought that the current Easter rules
made it impossible for it to fall on the 15th of Nissan.


I think it was two years ago that the first night of Passover was on
Holy Thursday (or vice versa), which precisely reproduced the
historical occasion.

Why would the "current" Easter rules have such a restriction? There's
certainly nothing about it in the several pages of small type in the
front of the Book of Common Prayer (1928), which I read plenty of
times while waiting for Morning Prayer to end.
  #26  
Old February 19th 10, 06:10 PM posted to sci.math,sci.physics,sci.astro,sci.lang,alt.usage.english
Peter T. Daniels
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Posts: 200
Default The perpetual calendar

On Feb 19, 10:30*am, Yusuf B Gursey wrote:
On Feb 19, 8:24*am, "Peter T. Daniels" wrote:





On Feb 19, 4:34*am, James Hogg wrote:


John Atkinson wrote:
Halmyre wrote:
On 19 Feb, 04:58, "Ray O'Hara" wrote:
"Andrew Usher" wrote in message


...


Owing to the inconveniences which attend the shifting of the
calendar, and attempting in passing to create a more perfect
Church calendar, I say the following: 1. That Christmas day
should be fixed to a Sunday, and this should be the Sunday
between Dec. 21 and 27, and that in all civilised countries the
Monday should be considered a holiday, or the Saturday if not
normally. 2. That similarly Easter day should be fixed to the
Sunday which is 15 weeks following Christmas. 3. That the leap
year rule be changed to have a leap year occur every fourth
save that it be delayed when the leap year would start on a
Thursday, and that this gives 7 leap years in every 29, which
is near enough. 4. That the perpetual calendar can be made, by
considering the first day of the year of weeks to occur on the
Sunday after the Assumption, and if this is the first possible
calendar day, it is called week 1, and otherwise week 2, and
every year runs through week 53. And this calendar ensures that
everything can be fixed to a day of a certain week, in
particular the American Thanksgiving must be made 31 days
before Christmas. 6. This is surely the best possible
arrangement that can be made, without disturbing the cycle of
weeks or that of calendar days inherited from the Romans.
Andrew Usher
The calendar has several sources, not just the Rome and the onewe
habe in fine as it is
I just wish they'd settle on a date for Easter and be done with it..


But, the whole point of Easter is that it has a full moon! *You might
as well scrap the whole thing otherwise. *Or are you suggesting that
we only take holidays at Easter every four years or so, when your
“settled” date just happens to correspond with the right lunar phase?


My Book of Common Prayer makes things easy by pointing out that "the
moon referred to in the definition of Easter Day is not the actual moon
of the heavens, but the Calendar Moon, or Moon of the Lunar Cycle, which
is counted as full on its fourteenth day, reckoned from the day of the
Calendar New Moon inclusive." Also, in a Bissextile Year "the number of
Sundays after Epiphany will be the same, as if Easter Day had fallen one
day later than it really does."


Which is why Easter and Passover rarely coincide -- we happen to have
had a spate of coincidence in recent years, but that'll soon be over.


What could be simpler?


The Muslim calendar -- no intercalated months, and no connection with
the solar year. So Ramadan drifts through the seasons.


Ramadan is celebrated according to the actual siting of the crescent,
not the (various) algorithms used for civil purposes, though I think
some "cheat" by using the algorithms (there are a couple most
frequently used). last time in Iraq the Shia and the Sunni observed it
at different dates. so it is rather complicated.-


They _do_ publish calendars that cover more than the next 29 1/2 days,
don't they? Such information _can_ be calculated (and was calculated
3000 years ago in Mesopotamia), and varies from site to site depending
on latitude, weather, and surrounding terrain (i.e., where's the
horizon?).
  #27  
Old February 19th 10, 06:17 PM posted to sci.math,sci.physics,sci.astro,sci.lang,alt.usage.english
Yusuf B Gursey
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Posts: 78
Default The perpetual calendar

On Feb 19, 12:10*pm, "Peter T. Daniels" wrote:
On Feb 19, 10:30*am, Yusuf B Gursey wrote:





On Feb 19, 8:24*am, "Peter T. Daniels" wrote:


On Feb 19, 4:34*am, James Hogg wrote:


John Atkinson wrote:
Halmyre wrote:
On 19 Feb, 04:58, "Ray O'Hara" wrote:
"Andrew Usher" wrote in message


...


Owing to the inconveniences which attend the shifting of the
calendar, and attempting in passing to create a more perfect
Church calendar, I say the following: 1. That Christmas day
should be fixed to a Sunday, and this should be the Sunday
between Dec. 21 and 27, and that in all civilised countries the
Monday should be considered a holiday, or the Saturday if not
normally. 2. That similarly Easter day should be fixed to the
Sunday which is 15 weeks following Christmas. 3. That the leap
year rule be changed to have a leap year occur every fourth
save that it be delayed when the leap year would start on a
Thursday, and that this gives 7 leap years in every 29, which
is near enough. 4. That the perpetual calendar can be made, by
considering the first day of the year of weeks to occur on the
Sunday after the Assumption, and if this is the first possible
calendar day, it is called week 1, and otherwise week 2, and
every year runs through week 53. And this calendar ensures that
everything can be fixed to a day of a certain week, in
particular the American Thanksgiving must be made 31 days
before Christmas. 6. This is surely the best possible
arrangement that can be made, without disturbing the cycle of
weeks or that of calendar days inherited from the Romans.
Andrew Usher
The calendar has several sources, not just the Rome and the onewe
habe in fine as it is
I just wish they'd settle on a date for Easter and be done with it.


But, the whole point of Easter is that it has a full moon! *You might
as well scrap the whole thing otherwise. *Or are you suggesting that
we only take holidays at Easter every four years or so, when your
“settled” date just happens to correspond with the right lunar phase?


My Book of Common Prayer makes things easy by pointing out that "the
moon referred to in the definition of Easter Day is not the actual moon
of the heavens, but the Calendar Moon, or Moon of the Lunar Cycle, which
is counted as full on its fourteenth day, reckoned from the day of the
Calendar New Moon inclusive." Also, in a Bissextile Year "the number of
Sundays after Epiphany will be the same, as if Easter Day had fallen one
day later than it really does."


Which is why Easter and Passover rarely coincide -- we happen to have
had a spate of coincidence in recent years, but that'll soon be over.


What could be simpler?


The Muslim calendar -- no intercalated months, and no connection with
the solar year. So Ramadan drifts through the seasons.


Ramadan is celebrated according to the actual siting of the crescent,
not the (various) algorithms used for civil purposes, though I think
some "cheat" by using the algorithms (there are a couple most
frequently used). last time in Iraq the Shia and the Sunni observed it
at different dates. so it is rather complicated.-


They _do_ publish calendars that cover more than the next 29 1/2 days,
don't they? Such information _can_ be calculated (and was calculated


some allow calculation, but conservatives wait for a fatwa from the
religious authorities to commence Ramadan, and this is the practice in
many muslim countries. as I said before, in Iraq this resulted in the
Shia and the Sunni observing Ramadan with a days difference.for other
religious days, the algorithm may be used, but there are several
versions of that, some being more common than others.

3000 years ago in Mesopotamia), and varies from site to site depending
on latitude, weather, and surrounding terrain (i.e., where's the
horizon?).


  #28  
Old February 19th 10, 06:20 PM posted to sci.math,sci.physics,sci.astro,sci.lang,alt.usage.english
Yusuf B Gursey
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Posts: 78
Default The perpetual calendar

On Feb 19, 10:59*am, António Marques wrote:
Yusuf B Gursey wrote (19-02-2010 15:35):

the Orthodox (Eastern) churches have a slightly different system.
dunno exactly what it is.


Afaik the system is the same, it's March 21 that is different.


but for the Orthodox, the Gregorian calendar has been accepted for
other holidays. the Monophysites (Copts, Armenians, Jacobite Syrians)
observe Christmas at a different date for other reasons.
  #29  
Old February 19th 10, 06:52 PM posted to sci.math,sci.physics,sci.astro,sci.lang,alt.usage.english
Halmyre[_2_]
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Posts: 2
Default The perpetual calendar

On 19 Feb, 09:12, John Atkinson wrote:
Halmyre wrote:
On 19 Feb, 04:58, "Ray O'Hara" wrote:
"Andrew Usher" wrote in message


....


Owing to the inconveniences which attend the shifting of the calendar,
and attempting in passing to create a more perfect Church calendar, I
say the following:
1. That Christmas day should be fixed to a Sunday, and this should be
the Sunday between Dec. 21 and 27, and that in all civilised countries
the Monday should be considered a holiday, or the Saturday if not
normally.
2. That similarly Easter day should be fixed to the Sunday which is 15
weeks following Christmas.
3. That the leap year rule be changed to have a leap year occur every
fourth save that it be delayed when the leap year would start on a
Thursday, and that this gives 7 leap years in every 29, which is near
enough.
4. That the perpetual calendar can be made, by considering the first
day of the year of weeks to occur on the Sunday after the Assumption,
and if this is the first possible calendar day, it is called week 1,
and otherwise week 2, and every year runs through week 53. And this
calendar ensures that everything can be fixed to a day of a certain
week, in particular the American Thanksgiving must be made 31 days
before Christmas.
6. This is surely the best possible arrangement that can be made,
without disturbing the cycle of weeks or that of calendar days
inherited from the Romans.
Andrew Usher
The calendar has several sources, not just the Rome and the onewe habe in
fine as it is


I just wish they'd settle on a date for Easter and be done with it.


But, the whole point of Easter is that it has a full moon! *You might as
well scrap the whole thing otherwise. *Or are you suggesting that we
only take holidays at Easter every four years or so, when your “settled”
date just happens to correspond with the right lunar phase?


We don't have Christmas only when there's a bright star in the east.

It's like saying "I was born on a Wednesday, so I'll only celebrate my
birthday when it falls on a Wednesday".

--
Halmyre
  #30  
Old February 19th 10, 07:02 PM posted to sci.math,sci.physics,sci.astro,sci.lang,alt.usage.english
Cheryl
external usenet poster
 
Posts: 46
Default The perpetual calendar

Halmyre wrote:
On 19 Feb, 09:12, John Atkinson wrote:
Halmyre wrote:
On 19 Feb, 04:58, "Ray O'Hara" wrote:
"Andrew Usher" wrote in message
...
Owing to the inconveniences which attend the shifting of the calendar,
and attempting in passing to create a more perfect Church calendar, I
say the following:
1. That Christmas day should be fixed to a Sunday, and this should be
the Sunday between Dec. 21 and 27, and that in all civilised countries
the Monday should be considered a holiday, or the Saturday if not
normally.
2. That similarly Easter day should be fixed to the Sunday which is 15
weeks following Christmas.
3. That the leap year rule be changed to have a leap year occur every
fourth save that it be delayed when the leap year would start on a
Thursday, and that this gives 7 leap years in every 29, which is near
enough.
4. That the perpetual calendar can be made, by considering the first
day of the year of weeks to occur on the Sunday after the Assumption,
and if this is the first possible calendar day, it is called week 1,
and otherwise week 2, and every year runs through week 53. And this
calendar ensures that everything can be fixed to a day of a certain
week, in particular the American Thanksgiving must be made 31 days
before Christmas.
6. This is surely the best possible arrangement that can be made,
without disturbing the cycle of weeks or that of calendar days
inherited from the Romans.
Andrew Usher
The calendar has several sources, not just the Rome and the onewe habe in
fine as it is
I just wish they'd settle on a date for Easter and be done with it.

But, the whole point of Easter is that it has a full moon! You might as
well scrap the whole thing otherwise. Or are you suggesting that we
only take holidays at Easter every four years or so, when your “settled”
date just happens to correspond with the right lunar phase?


We don't have Christmas only when there's a bright star in the east.

It's like saying "I was born on a Wednesday, so I'll only celebrate my
birthday when it falls on a Wednesday".

--
Halmyre


I suppose it all comes down to how much predictability each person
likes. Some people like all their holidays to come at the same time each
year, and others are happy to put up with Easter, for example, coming
late some years because other years it comes nice and early, which makes
a much-needed break in a long winter. I never did consider Easter to be
necessarily a spring holiday, myself.

Of course, people living in places where they already have public
holidays in all three of the dreary months of January, February and
March wouldn't greet an early Easter with as much enthusiasm as I do.

And I know Easter doesn't occur in January or February, but they seem
much longer than they are when Easter comes in the latter part of April;
and slightly shorter than they are when I have a March Easter to look
forward to.

I want an official long holiday weekend in every single month, no
exceptions.

--
Cheryl
 




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