The Hebrew Calendar - Part 3

In Part 1 of our series we discussed how the Hebrew calendar has a different number of days in a year than the Gregorian calendar. The twelve month Hebrew year has 354 days. In seven years out of a nineteen year cycle, a thirteenth month is added to make up for the lost days. In part 2 we provided reconciliation in the number of days between the Hebrew and Gregorian calendars over a nineteen year span of time. We showed that the two calendars come to very close synchronization over nineteen years. Our next order of business is to discuss just how accurate the Hebrew calendar is when compared with the Gregorian calendar.

Rabbi Hillel II developed the modern Hebrew/Jewish calendar in the Jewish year of 4119, or AD 359 on the Gregorian calendar. Using his calendar methods (as described in Part 2) and assuming that the Gregorian calendar we use today was in effect at that time, the dates of Rosh Hashanah would have ranged from August 29 to September 28, between the Hebrew years 4100 and 4200. In the present Jewish calendar, the 58th century, the dates of Rosh Hashanah range from September 5 to October 5, a gain of six or seven days. This slight difference of approximately one hundred minutes over nineteen years has accumulated to almost a week over a 1,650 year period. It takes almost 9,300 years for this discrepancy to accumulate to a full month in time.

Here is viewpoint on the Hebrew calendar as it corresponds to the agricultural season:

1st month on sacred calendar/7th month on civil calendar–Nisan Barley Harvest
2nd month on sacred calendar/8th month on civil calendar–Iyar Barley Harvest
3rd month on sacred calendar/9th month on civil calendar–Sivan Wheat Harvest
4th month on sacred calendar/10th month on civil calendar–Tamuz Grape Harvest
5th month on sacred calendar/11th month on civil calendar–Av Olive Harvest
6th month on sacred calendar/12th month on civil calendar–Elul Dates/Figs Harvest
7th month on sacred calendar/1st month on civil calendar–Tishri Early Rains
8th month on sacred calendar/2nd month on civil calendar–Heshvan Plowing
9th month on sacred calendar/3rd month on civil calendar–Kislev Wheat/Barley Sowing
10th month on sacred calendar/4th month on civil calendar–Tevet Winter Rains
11th month on sacred calendar/5th month on civil calendar–Shevat Almond Bloom
12th month on sacred calendar/6th month on civil calendar–Adar Citrus Harvest
13th month on sacred calendar–Intercalary Month

The celebrations of Passover, the Feast of Firstfruits and the Days of Unleavened Bread all occur in Nisan – during the barley harvest.

Pentecost occurs in Sivan, the time of the wheat harvest.

The last three grand Jewish celebrations: the Feast of Trumpets, the Day of Atonement and the Feast of Tabernacles all occur in Tishri, at the end of the major harvest.

A Couple of Last Points

There are two last peculiarities to the Hebrew calendar. Yom Kippur (the Day of Atonement) is the most holy day on the Hebrew calendar. This day should not fall adjacent to the seventh-day Sabbath because Atonement is a day when fasting, doing without food or water, occurs. This would cause difficulties in coordination of the weekly Sabbath.

The seventh day of the Feast of Tabernacles should not fall on a Saturday because that would interfere with the holiday's observances. A day is added to the month of Heshvan or subtracted from the month of Kislev of the previous year to prevent these events from happening. This process is sometimes referred to as "fixing" Rosh Hashanah.

There we have it. If you have read this three part series on the Hebrew calendar I'm more than confident that you now understand it very well. Now when you visit Israel you will have a much better idea of coordinating dates,

The Hebrew Calendar (Part 2)

In part 1 of our series on the Hebrew Calendar we saw how the Hebrew calendar has a different number of days in a year than the Gregorian calendar. The twelve month Hebrew year has 354 days, eleven or twelve days less than the Gregorian calendar. In seven years out of a nineteen year cycle, a thirteenth month is added to make up for the lost days. In the third, sixth, eighth, eleventh, fourteenth, seventeenth and nineteen years out of a nineteen year cycle there are thirteen months.

The Hebrew calendar months alternate between 29 and 30 days:

Month     Number of Days

Nisan              30
Iyar                 29
Sivan               30
Tamuz             29
Av                   30
Elul                  29
Tishri               30
Heshvon          29
Kislev              30
Tevet               29
Shevat             30
Adar             29/30
Adar II             29

In a twelve month year, the month of Adar has twenty-nine days. In a leap-year (thirteen month year), Adar has thirty days and Adar II (the added thirteenth month) has 29. So the twelfth month, Adar can have either 29 or 30 days depending on if the year is a leap-year or not. With that reasoning the Hebrew year can have either 354 or 384 days.

Now we need to begin to see if we can see how close we can come to reconciling the number of days between the two calendars. Although some have had loosely said the number of days matches up over nineteen years, that is not exactly the case, there is a slight difference. Let's see how close they come.

• A lunar month is actually 29 days, 12 hours, 44 minutes and 2.8 seconds. This is how long it takes the moon to circle the earth and is what lunar months are based on. In decimal format this is 29.530587963 days.
• Twelve lunar months make up 354.37 days. Twelve months on the Gregorian calendar are 365.2425 days.
• The number of days in the Gregorian calendar over nineteen year is:
19 (years) x 365.2425 (days per year) = 6,939.61 day
• The number of days in a twelve-month lunar calendar over nineteen years is:
19 (years) x 29.530588 (days per month) x 12 (months) = 6,732.97 days
• In the modified lunar (lunisolar) calendar, the Jews insert a thirteenth month (Adar II) in seven years out of every nineteen year cycle. The additional number of days accounted for by this thirteenth month is:
7 (years with thirteen months) x (29.53088 (days per month) = 206.71 days.
• When we add the number of days in nineteen, twelve-month lunar calendar years to the days added during the seven years when there are thirteen months we have:
6,732.97 + 206.71 = 6,939.68 days

The Gregorian and modified lunar calendars thus reconcile to within .07 of a day over nineteen years.
6,939.68 – 6,939.71 = .07


Summary: Number of Days over Nineteen Years
Gregorian (Solar) Calendar
Days per year = 365.2425
Days in 19 years = 6,939.61

Hebrew (Lunisolar) Calendar
Days per month = 29.530588
Days per year (12-month year) = 354.367056
Days per year (13-month year) = 383.897644
Total days in 12 12-month years = 12 x 354.37 = 4,252.40
Total days in 7 13-month years = 7 x 383.90 = 2,687.28
Total days in 19 years = 6,939.68

Difference over 19 years = .07 day


Part 3 of this series will discuss the significance of .07 of a day plus a couple more tid-bits of information.

For more information about the roots of Christianity check out www.feelingoutstanding.com/ID.html.

Tom Thorne