Outline of the Jewish Calendar

By Liaf

We’ve made mention several times of the Jewish calendar. The last Halloween message made mention of it as well as the series we had on the feast days. Those who have heard Morfessa and I teach probably understand a little about it --- at least you understand it is a lunar based calendar. For the rest of our readers out there, I thought it would be a good idea to post an old outline that I had for quite some time now. Actually, I do not know all the calendar rules that are used to create the calendar. The method seems to use the same type of logic in creating computer programs, i.e., a lot of "ifs" "thens" and conditions. I’m not good at remembering rules. However, the outline gives the overall view what makes this calendar tick. In addition, those of you who are into astronomy can ascertain about what month it is by virtue of the moon’s position and the season. The calendar rules are still framed around those facts. I use the same method and find that I am very rarely more than a day off even if I had no idea what the Jewish calendar says for that year.

In ancient times, the calendar was based on observation and from that the priests made short termed calculations and announced the official starting date of a month. However, some sects believe there was secret calculation. I have no aversion to that belief, although the evidence may not convince a skeptic. Today the calendar is definitely calculated based on the rules and sighting of the new moon is not required. My jury is still out regarding the use of ancient, secret calculation. It would not be unlikely since I do believe there were ancient sacred standards and measures (to be covered in another message soon).

OK---- Here is your "crash course" on the Jewish calendar:

I. Jewish calendar is Lunar:

  1. A lunar cycle is about 29 ½ days, hence the Jewish month is either 29 days (called a defective month) or 30 days (called a full month).
  2. The end of the old month and beginning of the new month corresponds to new moon.
  3. The 7th of the month corresponds to first quarter.
  4. The 14th-15th of the month corresponds to full moon.
  5. The 22nd of the month corresponds to last quarter.
  6. A day starts at sundown, not midnight. For example, Friday evening about 6:00 PM is the start of a Saturday Sabbath.

II. Month Names and Duration:

  1. Names are Babylonian. They had a similar calendar.
  2. 1) Nisan (30), 2) Iyyar (29), 3) Sivan (30), 4) Tammuz (29), 5) Av (30), 6) Elul (29), 7) Tishri (30), 8) Heshvan (29 or 30), 9) Kislev (29 or 30), 10)Tevet (29), 11) Shevat (30), 12) Adar (29; 30 in leap years), 13) Adar II (a leap month added 7 times in a 19 year cycle consisting of 29 days).
  3. Heshvan and Kislev are adjustable months to keep calendar in sync with the lunar cycle.

III. Years and Intercalation:

  1. A religious New Year begins on Nisan 1 which is the new moon near the first day of spring.
  2. A civil New Year begins on Tishri 1 (the 7th month) which is the new moon near the first day of autumn.
  3. A year normally consists of 12 months of 353-355 days.
  4. To keep in step with the seasons, an extra leap month is added 7 times in a 19 year period given that 235 lunar cycles is almost exactly 19 solar years, i.e., 19 yrs. X 12 months + 7 months extra= 235. This extra month is called Adar II, hence a leap year consists of 383-385 days.

IV. Feast Days:

  1. Weekly Sabbath is Saturday.
  2. Passover Nisan 14
  3. Unleavened Bread Nisan 15. This feast goes on for 7 days and is often called Passover week.
  4. Firstfruits Falls on a Sunday during Passover week.
  5. Pentecost The name means ‘fifty’ and falls on a Sunday (50th day) 7 weeks after Firstfruits.
  6. Trumpets Tishri 1
  7. Day of Atonement Tishri 10; also called the Sabbath of all Sabbaths.
  8. Tabernacles Tishri 15. This is also a one week festival.
  9. Minor New Moon celebrations to herald a new month.
  10. The feasts in B-H were the only ones given by the LORD Himself. The Jews added several others later on such as Purim and Hanukkah.
  11. Feast day restrictions: Hoshana Rabbah (part of the feast of Tabernacles that falls on Tishri 21) cannot fall on a weekly Sabbath because the ceremony involves the work of beating willow branches. The Day of Atonement cannot fall on a Friday or Sunday so as to compete with the weekly Sabbath. It may, however, fall on a weekly Sabbath. Because of these restrictions, Nisan never begins on a Monday, Wednesday, or Friday. Likewise, Tishri never begins on a Sunday, Wednesday, or Friday.

V. Misc:

  1. The calendar is now calculated to agree with the lunar cycle and seasons. This was introduced by Hillel II (330-365 AD).
  2. Previously, sighting of the new moon was required under most circumstances for the commencement of the month. Intercalation was more erratic then.
  3. Fires used to be lit from hilltops to communicate in rural regions the sighting of the new moon.
  4. Sometimes sectarian groups lit fires at different times and there was doubt as to the true start of the month. Hence feasts were often celebrated for two days.

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