vid

When looking at people trying to compute rough Jesus birth date from Zecheriah priestly service, it seems to me that different people arrive to different dates (sometime very different) using same method. This looks like there is some uncertainity in Jewish calendar and priestly services.

Could somebody explain (or point me to some online explanation) of how Jewish calendar worked? I have read it was somehow moon-based, it was couple of days shorter than sun year and these were somehow filled in every couple of years, not sure if it filled in one day every 4th year, etc. I am really confused about all this.

Is there some uncertainity about that calendar (and some "fixed points" in it)? Also, what are sources we know this calendar from?

semiopen

There was a Babylonian Calendar post on here a few weeks ago, and I asked a question about the Gregorian calendar vs the Jewish calendar which nobody replied to. One problem with calculating dates is that the Gentile calendar flipped from Julian to Gregorian sometime in the reformation which can result in an errors.

The Jewish calendar is based on the moon, there are twelve months in a year but seven times in 19 years a leap month is added. This is known as Adar I, Adar II is the normal Adar which contains the holiday of Purim.

This link discusses this in more depth (and accuracy)

http://www.jewfaq.org/calendar.htm

My question was whether the Jewish calendar is as accurate as the Gregorian calendar. I suspect that it is.

The link states the calendar was in use at least from about 400 CE, before the fixing of the calendar, months were changed by witnesses ("two witnesses or three witnesses") who testified to the Sanhedrin about sighting a new moon. Obviously this could result in some differences.

vid

Thank you semiopen, so far the clearest description I saw.

This seems to me like very complicated topic, but very much downplayed by authors who would like to use Jewish Calendar for calculations. Too bad it doesn't have any references, looking up stuff in Talmud was always hell-hard for me, compared to looking up stuff in Bible.

Is there really no one here who could shed more light on this? Most articles I saw until now treated Jewish calendar in 1st century as pretty much fixed, but this article you posted suggest it was far from that. However, without references, I can hardly use it in any serious article.

Maybe someone here at least knows some Jewish religious/historical forum, where people are more likely to know more details on topic?

vid

following links and research proved to be useful, as usual

http://www.jewfaq.org/calendr2.htm
http://en.wikipedia.org/wiki/Hebrew_calendar (and links)

also some books seems neat, too bad I can't spend moeny for a chapter in article
Understanding the Jewish Calendar (or via: amazon.co.uk)
The Comprehensive Hebrew Calendar By Arthur Spier

I quess, I will have to spend an evening reading to learn about the situation.

semiopen

It appears that at some point the sages added up the years from the bible and came up with the total. The difference with this total and Bishop Ussher's mostly seems to be the number of years in Egypt. The Bishop used 430 I think, from Exodus 12:40, but Jews figure that Jochebed (Moses mother) was born while traveling to Egypt from Canaan and come up with something a few hundred years less.

Here is a Christian who has looked at the issue

http://users.aristotle.net/~bhuie/210.htm

I've also seen some reputable guys agree with the Bishop, but I find it disorientating to imagine Christians can understand the Hebrew bible better than Jews, maybe it's the exception that proves the rule.

DCHindley

I'm going to try this again, my first response eaten by the gods of the Internet ether.

While some traces exist in the Law that suggest Judaism once used a fixed ("schematic") 364 day year calendar (52 weeks, or four "seasons" each consisting of three thirty day months ended by a special day, or something along that order), since the return from the Babylonian captivity they were using a lunar calendar similar to that used by the Babylonians.

A lunar year consists of 12 lunar months, averaging about 29.5 days each. The 1st of each month was determined by observation of the first crescent of a new moon. Usually the months alternated between 29 and 30 days, but atmospheric conditions could mean a couple 29 day months in succession or even a 28 day month. Anyways, 12 x 29.5 = 354 days. That is 11.25 days less than a solar year.

The Babylonians had figured out around 747 BCE that 235 lunar months equalled 19 solar years almost exactly (off by 7.25 days). That meant that 7 of those 19 solar years required an extra, 13th, lunar month to bring them into sync, more or less. However, for a long time they didn't really have a formal system for choosing those 7 years to add the extra month in a 19 year span. The extra month was sometimes added in mid-year and sometimes at the very end. Sometimes it was 30 days, sometimes it was 29. Generally it was every 3 years give or take depending on when the priests recommended it and the king was willing to sign off on it.

This went on until sometime between 383 and 367 BCE, when a formal 19 year intercalation cycle was established where all these matters were specified. This is called a "luni-solar" calendar = a lunar calendar synchronized to the solar year by intercalation. They still determined the start of each month by observation.

The Jews were in captivity in this period before establishment of the formalized 19 year cycle, and apparently took it with them when they returned back to the holy land starting 538/537 BCE. However, they did not adopt the formal 19 year fixed cycle with the Babylonians after 367 BCE. They continued the older Babylonian system of adding in those 7 extra months whenever it seemed fitting, around every 3 years give or take. I believe they made one change, always adding a second Adar at the end of the year.

Once the temple was destroyed and Jerusalem sacked in 70 CE, formal observations stopped and Jews adopted the local calendars of wherever they lived. The Macedonians/Greeks also used a lunisolar calendar with the Babylonian intercalations (usually), but decided to adopt a schematic calendar based on computations of 1st visibility of the moon rather than actual observation. The Romans used their odd ball fixed months of varying length with a pretty crappy intercalation system until the Julian version of the calendar was stabilized somewhere in the 1st century CE. The Egyptians used both lunar months, and also schematic months of 30 days with 5 intercalary days at year end, and after the Romans took over also had a local version of the Roman calendar.

I believe the Jews continued to intercalate at the direction of their Roman appointed patriarch, using local lunar months established by calculation, until they too formally adopted the Babylonian style 19 year cycle still used by Jews today, somewhere around 400 CE. The online "Jewish calendars" are based on that system, but would not be accurate before around 400 CE.

The Babylonian calendar continued to be formally used in Babylon until around 75 CE. You can find a reasonably accurate reconstruction of the actual 1st crescent dates and intercalations back to 1st year of Nabopolassar (626/625 BCE) in Babylonian Chronology: 626 B.C. - A.D. 75, by Richard A. Parker and Waldo H. Dubberstein (Brown Univ Press, 1956). This will NOT necessarily correlate with the 1st days of Jewish months (could be a day or so to either side of the Babylonian days) or Jewish intercalation practice of the time. We can get pretty close, as we know what rules Jews were using to make sure passover fell after the vernal equinox (around March 21 of the Julian calendar each year). Still, one must take all those careful calculations of the day of passover with a grain of salt.

We knew from Josephus that Jews had organized the priests into "courses" so each could serve their 2 weeks a year in rotation. The Hebrew bible speaks of courses of priests, although Josephus's list has two the bible does not, meaning the number of courses was being changed over time, but by the 1st century BCE I think it roughly approximated the ancient 364 day calendar. This kind of 364 day calendar was found to be in use by some Jews (the book of Jubilees uses a 364 day calendar, as does 1 Enoch, and a slew of schematic calendars - many referring to priestly courses - have been discovered among the DSS). A couple DSS fragments even try to correlate the 364 day calendar to a luni-solar one that intercalated the extra Adar every 3 years, rain or shine. Unfortunately, no reference points exist to allow us to connect any date so mentioned in the DSS fragments to a known Roman date, so we still don't know jack.

DCH

Sheshbazzar

It must be noted that not all "Jews" observed or employed the same "calendar" or "observed" the Feasts of YHWH on the same days.
The differences in how time was/is perceived and calculated could/can be quite profound.
I observe a "calendar" that includes a 360 day "year", and a 367.5 day "year" as well as the solar and lunar "years" of other lengths, always equal from year to year.
Wheels within wheels, or as gears within gears, in a perfect orrery, precise to the last second over any period of time.
Seven and one half weeks is fifty-two and one half days days is twelve hundred and sixty hours the seventh part of fifty-two and one half weeks.
Three hundred and sixty-seven and a half days, is seven and a half days over three hundred and sixty days.
Seven and one half days is one hundred eighty hours, or ten thousand eight hundred minutes, or six hundred, forty-eight thousand seconds.
Fifteen days is three-hundred and sixty hours, three-hundred and sixty hours seven times is twenty-five hundred and twenty hours or fifteen full weeks.

Remember the Month of Abib... on the tenth day of this Month....on the fourteenth day... on the fifteenth day of this Month. And in The Seventh Month.
I lifted up my hands unto YHWH, and I looked, and I beheld my "fingers" digits, for the numbering of the number, and for the measuring of the measure.

And what did I perceive in fifty-two and a half days, and in fifty two and a half weeks, and in fifty-two and a half months, and in fifty two and a half years?
Or in fifty-two and a half inches, or in fifty-two and a half fingers?
By line I measured twenty fathoms, and further on fifteen fathoms, and through the mist perceived the approaching shore.

My reed is four sided and cut to one length, on one face equal divisions of one measure, and upon the other face equal divisions after the second measure, and so also the divisions of the third and the fourth face, all begin at one place and all end at one place.

Go figure said the Tick-Tock man

judge

This topic came up a while ago, here. I made the following comment which IIRC was correct (except for the lunar bit ).

IIUC the jews had 12 lunar months (of 28 days making 354 days in 12 months) and every 2 or 3 years and extra month was added. If the barley crop was not ready at the "expected" time an extra month was added. Naturally this would occur every 2 or 3 years.
So every 2 or three years they would have 13 (lunar) months instead of 12.

28 days would not make it a lunar calendar I dont think as lunar months are 29.5 days (although there is a variant which is close to 28 days ).

If you follow through this thread, and the links, you will see that we don't seem to know with 100% accuracy when these extra months were added, although there is some indication of when we think they were.

It is a while since I went over this , but I think I remember about it. I dont get over here that much so maybe shoot me an email if you have any questions that dont get resolved.

Anat

If I understand the multiple Talmudic anecdotes about disputes regarding the beginning of the month in the days of the Jamniya sanhedrin, the sanhedrin considered itself as the authority regarding the calendar in post-temple days. There are several tales of witnesses testifying to Gammaliel about observing the moon. Gammaliel accepted testimonies that agreed with his calculations and rejected those that disagreed with his calculated length of month (29+ days, to a fraction of a minute). There was also a dispute between Gammaliel and Rabbi Yehoshua where Gammaliel forced Yehoshua to travel on the day Yehoshua calculated to be Yom Kippur in order to reinforce Gammaliel's calendar among the public. Control of the calendar was the way to preserve the sanhedrin's dominance in manners pertaining to interpretation of Halakha.

DCHindley

You are right, I had completly forgotten about this exchange. So the Roman appointed patriarchs/ethnarchs continued to observe the first crescent even after the destruction.

DCH