Hebrew calendar

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 used to set the date for a Bar Mitzvah or Bat Mitzvah, the day a young person is considered an adult in Judaism. It sets the 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

Mosaic floor of a zodiac in the 6th century synagogue at Beit Alpha, Israel.

This figureⁿ², from 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.

The Hebrew calendar is a lunisolar calendar which depends on both the moon and the sun. Months of the Hebrew calendar are based on the appearance of the new moon. At the same time, the holiday of Passover must be in the spring.

History

According to the Book of Exodus, Jews have been using a lunisolar calendar since the time they left Egypt. The first commandment the Jewish people received as a nation was the commandment to determine the New Moon. Very soon after that, the Jews received the commandment to make sure that Passover falls in the spring.

In the Tanakh (the Hebrew Bible), the months are usually numbered rather than named. (See table below.) Only four month names appear in the Tanakh from before the Babylonian Exile (see table). 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. The Sanhedrin also decided when an extra month should be added to the calendar to keep Passover in the spring. (See Metonic cycle.) After the destruction of the Second Temple in 70