Calendar

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Explanation of Jewish Calendar

In Biblical Times the Jewish Calendar was established on the basis of established cycles of travel by the Moon and Sun around the Earth.

Each month in the Jewish calendar commences with the new Moon phase which connects all Jewish calendar dates to the Moon. However as the seasons are dictated by the Sun's travel, and Jewish Holidays are connected to particular seasons, the Jewish calendar requires some form of “adjustment” to bring it into sync with the Solar cycles.

This is done by way of adding a number of Leap Years into a cycle, with each Leap Year having an additional month added in that particular year. There are seven Leap Years in a nineteen-year cycle.

The Jewish calendar is therefore of a Lunar-Solar type and rather complex in “design” as the solar year is approximately 11 days longer than 12 lunar months.

In the early times of Jewish history the beginning of each month was determined by direct observation of the New Moon, which following a witness's testimony was officially confirmed and announced by the High Court (Sanhedrin) in Jerusalem.

The Jewish communities were notified of the beginning of the new month (Rosh Chodesh) by the kindling of night fires atop mountains and, in later times, by messenger.

A special committee of the Sanhedrin would keep track of ‘shortfall' between Lunar and Solar Calendars and when appropriate they would add a thirteenth month (Adar II) before Nissan in order to ensure that Nissan and Passover would occur in Spring.

This method of observation and intercalation was in use throughout the period of the Second Temple (516 B.C.E. - 70 C.E.) and about three centuries after its destruction, as long as there was an independent High Court.

In the fourth century after the Temple's destruction the Court's continued existence was threatened. As a result, the patriarch Hillel II took an extraordinary step to preserve the unity of the Jewish people. He made public the closely guarded secrets of Calendric calculation to ensure that Jews around the world continued to celebrate festivals on the same dates.

In accordance with this system, Hillel II formally sanctified all months in advance, and intercalated all future leap years until such time as a new, recognized High Court would again be established in Israel.

This is the permanent calendar according to which the New Moons and Festivals are calculated and celebrated today by Jews all over the world.

This calendar also applies certain rules by which complex astronomical calculations are combined with the religious requirements into an amazingly precise system.

So precise is the calendar, that every nineteen-year cycle in the Jewish calendar is exactly equal in time to nineteen years in the Gregorian (secular) Calendar.