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Introduction to the Jewish Calendar

Introduction to the Jewish Calendar


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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Mark USA October 12, 2016

When is the next "Sabbath year"? Reply

Subikash C Mishra June 25, 2016

First month in the Jewish calender, according to Bible? Reply

dozie Nigeria August 11, 2015

How to manage the Hotel business on a shabbath day Reply

Shaul Wolf April 19, 2015

Yom Kippur Katan is observed on the day prior to the beginning of the new month. The following months do not have a Yom Kippur Katan, for various reasons:
Iyar: the day preceding the month of Iyar is in the month of Nissan, when one is prohibited from fasting and mourning.
Tishrei: one may not fast or say penitential prayers on the day before Rosh Hashanah.
Cheshvan: being that Yom Kippur itself has just passed.
Teves: during the days of Chanukah one may not fast or mourn. Reply

Anonymous Montpelier, VT April 16, 2015

Which months are preceded by a Yom Kippur Katan? Reply Staff December 15, 2014

Rosh Hashanah (the first day of the seventh month) is the head of the year, while Nissan (the month in which Passover falls, is the first of the months. See Our Other Head for why this is so. Reply

Paul Pennsylvania December 5, 2014

Why does the Jewish New Year coincide with September when the first month usually coincides with April? Reply Staff December 2, 2014

The Jewish New Year usually coincides with September. Reply

Susara Pretoria South Africa November 27, 2014

when does the Jewish New Year start in relation to our Gregorian calendar? Reply

Paul Pennsylvania June 10, 2014

Thank you for your prompt answer. Is the Jubilee Year still observed? When will it occur next? Reply Staff June 10, 2014

The upcoming Jewish calendar year, Rosh Hashanah, will be a Sabbatical year. Reply

Paul Pennsylvania June 9, 2014

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. Reply

Di Barkas Australia May 24, 2014

Perhaps G-D is undecided on when "the end of time is' thus it can't be calculated. Reply

jones ghana January 26, 2014

can the jewish calander be used to calulate the end time Reply

Anonymous Los Angeles, CA January 21, 2013

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? Reply

Louise December 29, 2012

Why do you spell God as G-d? Reply

Rabbi Menachem Posner August 24, 2012

People are free to follow whichever calendar they wish. Reply

Anonymous port vila, vanuatu August 24, 2012

Does the whole world need to follow the Jewish calendar? Reply

Meira Shana Vista, California August 24, 2012

Isn't the Jewish calendar based on harvest times?

Makes sense to me. Reply

Anonymous HOPKINS, Minnesota April 8, 2012

I live in American and I noticed on this site the calendar has the Jewish days and American days all in one. Is there a place where I can purchase one just like the one on this site. Reply

Since Biblical times the months and years of the Jewish calendar have been established by the cycles of the moon and the sun. Torah law prescribes that the months follow closely the course of the moon, from its birth each month to the next New Moon.
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