Hebrew calendar

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The Hebrew calendar or Jewish calendar is the calendar used in Judaism. It is used to set the dates of the Jewish holidays, and the weekly public reading of the Torah. It is also used to set the date for a Yahrzeit (the anniversary of the death of a relative). The daily Jewish prayer service changes depending on the day of the Hebrew calendar.

Basic rules[change | change source]

The Hebrew calendar is a lunisolar calendar. That means that it depends on both the moon and the sun. Months of the Hebrew calendar are based on the appearance of the new moon.[1] At the same time, the holiday of Passover must be in the spring.[2] For this reason, years of the Hebrew calendar are based on the sun.

One solar (sun-based) year lasts about 365 days. But twelve lunar (moon-based) months only last about 354 days. For this reason, the Hebrew calendar adds an extra lunar month seven times in each cycle of 19 years. This rule makes the average Hebrew calendar year about the same length as a solar year, 365 days.[3]

History[change | change source]

Mosaic floor of a zodiac in the 6th century synagogue at Beit Alpha, Israel.
This figuren2, in a detail of a medieval Hebrew calendar, reminded Jews of the palm branch (lulav), the myrtle twigs, the willow branches, and the citron (etrog) used during the holiday of Sukkot.

Jews have been using a lunisolar calendar since Biblical times. The first commandment the Jewish People received as a nation was the commandment to determine the New Moon.[1] The months are usually referred to in the Bible by number rather than name. Only four month names from before the Babylonian Exile appear in the Tanakh (the Hebrew Bible): Aviv (first, literally "spring", but originally probably meant the ripening of barley), Ziv (second, literally "light"), Ethanim (seventh, literally "strong" in plural), and Bul (eighth), and all are Canaanite names. The month names of the modern Hebrew calendar were taken from the month names in the Babylonian calendar during the Babylonian Exile (6th century BCE).

At first, a new month began when witnesses came to the Sanhedrin (high rabbinical court) and testified that they saw the new crescent moon in the sky.[4] After the destruction of the Second Temple in 70 CE, it became harder for the Sanhedrin to meet and hear witnesses. For that reason, the Sanhedrin established a fixed, rule-based form of the calendar. The fixed calendar was adopted between 70 and 1178 CE, when its final form was fully described by Maimonides.[5]

In the modern Hebrew calendar, years are counted as Anno Mundi (Latin for "year of the world"). This represents the traditional count of years since the creation of the world as described in Genesis. This year is anno mundi 5776.

Notes[change | change source]

  1. 1.0 1.1 Exodus 12:1-2: "This month is the first month for you".
  2. Deuteronomy 16:1. "Spring" refers to northern hemisphere spring.
  3. 354 + 719 * 30 ≈ 365. This is an example; the exact rules are more complicated.
  4. The Islamic calendar, which is lunar, still uses a similar procedure today.
  5. The Code of Maimonides (Mishneh Torah), Book Three (Book of "Times" or "Seasons"), Treatise Eight: Laws of the Sanctification of the New Moon. See reference below.

References[change | change source]

  • The Code of Maimonides (Mishneh Torah), Book Three, Treatise Eight: Sanctification of the New Moon. Translated by Solomon Gandz. Yale Judaica Series Volume XI, Yale University Press, New Haven, Conn., 1956.
  • Bonnie Blackburn and Leofranc Holford-Strevens. The Oxford Companion to the Year: An Exploration of Calendar Customs and Time-reckoning. Oxford University Press; USA, 2000. pp 723–730.

Other websites[change | change source]

Date converters[change | change source]