| The history of the Jewish calendar traces back until the second millenium BCE. At these times, a luni-solar calendar seems to have been in use already, in which the decision of intercalating a month was made according to observations. Only four months had names (Abib, Ziv, Bul, Ethanim)(1), the other months having been designated with their numbers. In 587 BCE, Jerusalem was destroyed by the Babylonian king Nebukadnezar II. and many Jews deported to Mesopotamia, where, influenced by the Babylonian month names, the Jewish months got their names. After the Persian king Kyros had defeated the Babylonian Empire, the Jews were allowed to return to Jerusalem, were a small state was created, which consisted of the city itself an some area around it. This state was part of Persia and later of the Seleucid(2) Empire and Egypt. This is the period known as the time of the Second Temple (538 BCE until 70 CE). |
| Not only intercalation, but also the beginning of each month was determined by observation. A calendar council gathered on the 30th day of each month and consulted witnesses, which had to report on the visibility of the moon’s crescent. Had the crescent been visible, the actual day was declared to be the first day of the new month. Otherwise, the new month began only with the following day. The decision was published and sent to all communities by fire signals. But, according to reports from the second century CE, Samaritans gave false signals, causing many Jews to fall into error. The message was therefore carried to the communities by messengers, but with many Jewish communities too far away to be reached in time, the actual date became uncertain. Therefore, the Jews celebrated all feasts on two consecutive days, making sure, that any feast was observed. Only Yom Kipur was observed only on one day. |
| The Jewish state gained independence again in 140 BCE, and by the end of the century a Jewish kingdom had evolved. Soon the throne was disputed giving the Romans possibilities to get involved. In 63 BCE, Palestine was occupied by Roman troups led by Pompeius. The Jewish state remained formally independent, but in fact had to obey Roman orders. In this time, the Sanhedrin was created, which became the highest authority on problems whithin the Jewish state, including the determination of the calendar, which was observation-based, yet. |
| Following quarrels between Greek and Jewish inhabitants of Palestine, a full-scale Jewish uprising developed in 66 CE. The Romans sent Vespasian to suppress the rebellion. After Nero’s death a civil war broke out in the Roman Empire itself, which Vespasian could win, becoming emperor in 69 CE. Vespasian’s son, Titus, took over the lead of the Roman troups in Palestine. Eventually, Jerusalem and the Temple were destroyed in 70 CE. The Sanhedrin was re-created by the end of the first century CE and was now led by a patriarch. With the Jews now having communities almost all over the world then known, a regular scheme for the calendar became necessary. With such rules, anyone could determine the date regardless how far he lived from Jerusalem. |
| After the uprising led by Bar-Kokhba (132 CE) persecutions against the Jews reached an intensity which made it almost impossible to communicate the beginnings of months and years. Now, computational rules were being established concerning the calendar, and in the beginning fourth century CE the beginnings of the months were determined by calculation, the report of witnesses having become a mere formality. There was some opposition against this practice within the Sanhedrin, and Jews in Babylon and Alexandria were told to continue to celebrate the feasts on two days, which is done by the Jews in the diaspora until today. |
| When Constantine became Roman emperor, the Christian religion de facto became the official religion in the empire. It was forbidden to exercise the Jewish religion at all, including to do calculations in connection to the Jewish calendar. This led, in 359 CE, to patriarch Hillel II. publishing rules for computing the calendar which had been regarded as a secret until then (3). The 19-year leap year cycle was fixed to the present order, while the era and some rules for determining New Year were set only until the 10th century. The era used until the 11th century was the era of the Seleucids, starting in 312 BCE, while from the 10th until the 16th century, the Jewish Creation era came into use, which starts in 3761 BCE. |