Ben Whitfield Contributes  7/16/01

From: To: "Ben Whitfield" <bhwhit@coffey.com>
Sent: Thursday, July 12, 2001 7:13 PM
Subject: more calendar info


> Computing the Sacred (Biblical/Hebrew/Jewish) Calendar
>
> The familiar Western calendar is the Gregorian calendar, an adjusted
Julian
> calendar promulgated by Pope Gregory XIII in 1582, and adopted in Britain
> and America in 1752. It is essentially a solar calendar, in which one
> rotation of the Earth around the Sun is one year.
> There are 12 months in the year, but they have little to do with the
> rotation of the Moon around the Earth. Gregorian years are 365 or 366 days
> long. Months are 30 or 31 days, except February, which is 28 days or 29
days
> in a leap year.
>
> The Biblical calendar is based on both the rotation of the Moon around the
> Earth and of the Earth around the Sun. In principle, a month starts when a
> new moon is observed and lasts till the next new moon occurs. Therefore,
> months are 29 or 30 days long. Years are 12 or 13 months long and
> approximately align with the Sun.
>
> In Bible times, when two witnesses saw the new moon, then a new month was
> declared to start at the next sunset. If they saw it too close to sunset
for
> the New Moon rites to be prepared, then the new month was declared to
start
> at sunset on the following day. The decision as to whether there were to
be
> 12 or 13 months in the year depended on the state of the harvest and
whether
> enough lambs had been born for the sacrifices of the Passover observance.
It
> was this calendar that Jesus followed in the New Testament.
>
> Christian-instigated persecution of Jews forced the Jewish authorities to
> switch to a computed, rather than observed calendar. This computed
calendar
> matched as closely as possible the decision-making process that had been
> used previously. It is this computed calendar that is now followed by the
> vast majority of those who wish to observe the Biblical Holy Days.
>
> Suggestions have been made that the computations should be changed, or
that
> observation should again be used. It is clear that adjustments need to be
> made to the computed calendar in order to keep it synchronized with the
sun
> and moon. But there is no consensus as to how this should be done, and, in
> the modern world, this needs to be done years in advance. Returning to
> observation is idyllic, but totally impractical. The modern world requires
> plans for religious observances to be made months, or even years, in
> advance. Only a computed calendar permits this. It is clear that just as
> "the Sabbath was made for man", so also "the Calendar was made for man."
It
> is a tool to help us worship God. And an essential feature of a tool is
that
> it must be useful and practical.
>
> Month Number Post-Exile Name Pre-Exile Name Computed Days Features
> 1. Nisan = "Marching" Abib = "Green Ears" 30 days Passover and Days of
> Unleavened Bread, barley harvest
> 2. Iyyar, Ijar Zif = blossom 29 days Second Passover
> 3. Sivan   30 days Pentecost, wheat harvest
> 4. Tamuz, Tammuz = Babylonian god   29 days Fast of 4th month, "weeping
for
> Tammuz"
> 5. Av, Ab   30 days Destruction of 1st and 2nd Temple
> 6. Elul   29 days
> 7. Tishrei, Tishri, Tisri Ethanim = flowings 30 days Feast of Trumpets,
> Atonement, Tabernacles, Last Great Day
> 8. Cheshvan, Marchesvan Bul = rain 29/30 days "former" rains
> 9. Kislev, Chisleu   29/30 days Feast of Dedication, Lights = Hannukah
> 10. Tevet, Tebeth = muddy   29 days
> 11. Shvat, Sebat = downpour   30 days "latter" rains
> 12. Adar = darkened   29 days Purim
> Only in leap years:
> 13. Veadar = "Second Adar"   29 days
>
> Pre-Exilic names are the months names recorded in the Bible which were
used
> before the Jews went into Exile in Babylon (ca. 600 B.C.). The post-Exilic
> names are the Babylonian names for the same months, which continued to be
> used by the Jews after their return to Palestine.
>
> The difference of 11 1/4 days between 12 lunar months (354 days) and one
> solar year (365 1/4 days) accumulates in three years to more than a month.
> If no adjustments are made (as they are not in the Mohammedan calendar),
any
> month could occur in any season of the year. But the Biblical holydays are
> closely related to the seasons (for example, the Passover is commanded to
> occur in the month of "Green Ears" (Abib), i.e., in the spring). So an
> adjustment to the calendar must be made every few years. Every two or
three
> years, an extra month is added to a year. Such a month is called an
> "intercalary month." Those years are called leap years. In the computed
> calendar, the month Adar is added again, and called Veadar, "Second Adar".
> In earlier times, the thirteenth month could be, instead, "Second Elul".
>
> Jewish traditional holidays that occur in the month of Adar (such as
Purim)
> are celebrated in Veadar in a leap year. The same rule is applied to
> birthdays, anniversaries and other personal events.
>
> Since the Sun, Earth and Moon repeat their alignments almost exactly every
> 19 years, the leap years follow a 19 year "Metonic" cycle:
>
>
> Regular.
> Regular.
> Leap.
> Regular.
> Regular.
> Leap.
> Regular.
> Leap.
> Regular.
> Regular.
> Leap.
> Regular.
> Regular.
> Leap.
> Regular.
> Regular.
> Leap.
> Regular.
> Leap.
>
> In earlier times, there was no fixed cycle. However the "Sabbatical Year",
> every seventh year, was never a leap year.
>
> Postponements
>
> In addition to the leap year cycle, the length of each year is slightly
> adjusted to meet a number of constraints called Dechiot. These small
> adjustments are made by selecting the length of the two months of Cheshvan
> and Kislev to be 29 or 30 days. There are four possible combinations, but
> only three are actually used:
>
> year kind Cheshvan Kislev length of regular year
> chasera
> ("incomplete") 29 days 29 days 353
> kesidra
> ("in order") 29 days 30 days 354
> ---- 30 days 29 days ----
> shleima
> ("complete") 30 days 30 days 355
>
> The four constraints (Dechiot) that determine the exact year length have
to
> do with the exact timing of the holidays in relation to the phase of the
> moon and with relations to the day of the week.
>
> Dechia 1 - Molad Zaken
>
> The moon goes in orbit around the Earth. Every month, there is one
instance
> in which the moon is exactly between the Earth and the sun and the Earth
> faces the dark side of the moon. This instance is called Molad ("birth" of
a
> new moon) and it marks the beginning of a new month. The Molad of the
first
> month of the year, Tishrei, marks the Civil New Year or Rosh HaShana =
"Head
> of the Year". This is on Tishri 1. The religious New Year is on Nisan 1.
>
> Since the Earth is facing the dark side of the moon, the moon becomes
> visible later that day or the next day.
>
> In a year when the Molad of Tishrei occurs after 12:00 noon, Rosh HaShana
is
> postponed until the next day because the moon would not become visible
until
> the next day. This is done by adding one day to the previous year.
>
> Dechia 2 - Sunday, Wednesday, Friday
>
> If the Molad of Tishrei falls on Sunday, Wednesday or Friday, Rosh HaShana
> is postponed by one day to Monday, Thursday or Saturday, respectively.
>
> The reason is that if Rosh HaShana is on Wednesday or Friday, then Yom
> Kippur, "The Day of Atonement", would occur on Friday or Sunday. That
would
> make Yom Kippur adjacent to Shabbat, "Sabbath" (Saturday). Yom Kippur is a
> Fast (no eating) Day, in which we are to afflict ourselves and work is
> prohibited. The Sabbath is a day of rest and rejoicing, on which work is
> also prohibited. If they were to occur next to each other, the purpose of
> one or both days would be compromised.
>
> If Rosh HaShana is on Sunday, Hoshana Raba, the seventh day of the Feast
of
> Tabernacles would fall on Saturday, a rest day, and that would prevent the
> custom of demolishing the Tabernacles on the last day of that Feast. The
> eighth day is a solemn assembly on which the demolition cannot take place.
> So, if the seventh day were a sabbath, the Tabernacles would not be
> demolished till the ninth day, which is clearly opposed to the command to
> "dwell in Tabernacles for seven days."
>
> Dechia 3 - Molad of Regular Year on Tuesday
>
> If the Molad of Tishrei of a regular year with 12 months occurs on Tuesday
> morning, Rosh HaShana would occur on Tuesday. However, this would cause a
> problem with Rosh HaShana of the following year. It would occur on Friday,
> Saturday, or Sunday.
>
> To see why, remember that the length of a regular year, in the computed
> calendar, can be 353, 354 or 355 days. (12 lunar months are approximately
> 354 days. Only one day deviance is allowed from this.) So Rosh HaShana can
> only occur 3, 4 or 5 days later in the week next year, compared with this
> year.
>
> Friday and Sunday are always problems (Dechia 2). Therefore this year must
> have 354 days and the next Rosh HaShana will fall on Saturday. However,
the
> accurate length of a lunar month is 29 days, 12 hours, 44 minutes and 3
1/3
> seconds. The accurate length of a lunar year (12 lunar months) is
therefore
> 354 days, 8 hours, 48 minutes and 40 seconds. This means that if the Molad
> of this year occurs on Tuesday 6 AM, the Molad of the following year will
> occur on Saturday 2:48:40 PM, and Rosh HaShana will have to be postponed
to
> Sunday according to constraint number 1 and then postponed again to Monday
> according to constraint number 2. In order to do that, this year will have
> to be 356 days long, which is not possible.
>
> The conclusion of the above logic is constraint number 3 which states that
> if a Molad of a regular year occurs after Tuesday 3:22 AM, Rosh HaShana is
> postponed to Thursday.
>
> Dechia 4 - Molad of Leap Year on Thursday
>
> This is a similar situation to the one described in contraint number 4.
Here
> the rule is that if a Molad of a leap year occurs after Thursday 12:00
noon,
> the next Rosh HaShana is postponed from Monday to Tuesday.
>
> All the 4 constraints (Dechiot) can be pre-calculated and represented in
> tables of short cycles. Hebrew calendar software programs use relatively
> simple table lookup to determine the exact length of a given year and the
> date of Rosh HaShana. All the other dates and holidays are calculated by
> counting from Rosh HaShana.
>
> A Hebrew calendar computer program.
> Understanding the Jewish Calendar by Rabbi Nathan Bushwick. Moznaim
> Publishing Corporation, 1989.
>
>