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Introduction to the Jewish Calendar

Introduction to the Jewish Calendar

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Since Biblical times, various astronomical phenomena have been used to establish uniquely Jewish definitions for the day and its hours, the months and the year.

The length of days and hours vary by the season, controlled by the times of sunset, nightfall, dawn and sunrise. The months and years of the Jewish calendar are established by the cycles of the moon and the sun.

Though the months follow the lunar cycle, the lunar months must always align themselves with the seasons of the year, which are governed by the sun. Thus, the Jewish calendar is "Luni-Solar." The discrepancy between the solar year (365 days) and the lunar year (354 days) was resolved by every so often adding a thirteenth month to the year, to form a "leap year."

In the early times of our history, the High Court (Sanhedrin) in Jerusalem was assigned the tasks of determining the beginning of each month and the balancing of the solar with the lunar years. They relied on direct observation of the New Moon, astronomical data, and other considerations.

In the fourth century after the Temple's destruction, however, when oppression and persecution threatened the continued existence of the Court, a fixed calendar was instituted -- based on the Sanhedrin's closely guarded secrets of calendric calculation. This is the permanent calendar according to which the New Moons and festivals are calculated and celebrated today by Jews all over the world.

Like the original system of observation, it is based on the Luni-Solar principle. It also applies certain rules by which complex astronomical calculations are combined with the religious requirements into an amazingly precise system.

The following pages will provide a brief digest of the factors which control the determination of the Jewish hour, day, month and year.

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Discussion (31)
June 10, 2014
Jubilee Year
Thank you for your prompt answer. Is the Jubilee Year still observed? When will it occur next?
Paul
Pennsylvania
June 10, 2014
To Paul
The upcoming Jewish calendar year, Rosh Hashanah, will be a Sabbatical year.
Chabad.org Staff
June 9, 2014
Sabbath years and the Year of Jubilee
I am goyim, so I am not at all in touch with the larger cycles of the Jewish calendar. Is a Sabbath year and/or the Year of Jubilee going to occur in the next few years? I am trying to research an apocalyptic claim that was made based on these two events.
Paul
Pennsylvania
May 24, 2014
Perhaps G-D is undecided on when "the end of time is' thus it can't be calculated.
Di Barkas
Australia
January 26, 2014
can the jewish calander be used to calulate the end time
jones
ghana
January 21, 2013
Hebrew date for Yahrzeit on leap year
Was there a ruling or law or discussion in the past about what Hebrew date to use if the Yahrzeit date was on 30 Adar I and it is now not a leap year?
Anonymous
Los Angeles, CA
December 29, 2012
Why do you spell God as G-d?
Louise
August 24, 2012
To Anonymous, Port Vila, Vanuatu
People are free to follow whichever calendar they wish.
Rabbi Menachem Posner
August 24, 2012
calendar
Does the whole world need to follow the Jewish calendar?
Anonymous
port vila, vanuatu
August 24, 2012
Reasons?
Isn't the Jewish calendar based on harvest times?

Makes sense to me.
Meira Shana
Vista, California
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