The Jewish year 5771 began at sunset on Wednesday, September 8. Last year, the first day of ‘Rosh Hashanah’ was September 19; next year, it will fall on September 29. Why such divergence in dates?
Biblical texts, traditional interpretations and historical precedents provide answers. For example, the Jewish day begins at sunset in accordance with “And there was evening and there was morning, one day” (Gen. I:5). 5771 (from the Creation of the World) derives from the genealogical tables of Genesis (Chapters 5 and 11), carried forward.
The Jewish calendar is solar-adjusted lunar. The time between successive New Moons being approximately 29.5 days, the twelve Jewish months generally alternate between 29 and 30 days. This yields a lunar year of 354 days, eleven days shorter than the solar. Specific dates would thus traverse the seasons.
However, the Biblically-prescribed, date-specific, holidays, with their evident agricultural component, are season bound. Passover must fall in the Spring, Tabernacles (‘Sukkot”) must fall, at least partially, after the Autumnal Equinox. This dilemma is resolved by the addition of a thirteenth, leap month in seven years of a nineteen year cycle While corresponding solar dates vary within about a month or so, over that period the two calendars will have the same number of days. 5771, being a leap year, will end much later in 2011.
Careful readers of the Bible will notice that ‘Rosh Hashanah’ occurs on the first day of the seventh month (Lev. XXIII: 24), the months being reckoned from the month of Passover. However, Orthodox and Conservative Jews observe two days, while Reform, only one. In ancient times, declaration of a New Moon was done by the highest religious authorities on the basis of observation by witnesses. Such declaration was readily communicated within the Land of Israel. It took some time, though less than a month, to reach far flung Diaspora communities. Since the previous month could only have been of 29 or 30 days, a holiday could only fall on one of two adjoining days. The practice thus arose to observe both. Facing persecution and dispersion, and based on well understood astronomical principles, the current calendar was fixed in the fourth century C.E. Nonetheless, the practice has continued.
‘Rosh Hashanah’ itself poses a particular problem, being the only holiday falling on the New Moon. Due to uncertainty, even in Jerusalem, as to when witnesses would come forth, it has from time immemorial been observed even there for two days.
Interesting similarities exist in the ecclesiastical calendars of the monotheistic faiths. Linked to Passover, the date of Easter varies, falling on the first Sunday after the first full moon on or after March 21. The start of Ramadan in the pure lunar Islamic calendar is based on New Moon sighting. Historically there have been many different New Year dates, so it seems not amiss to wish readers a ‘Happy New Year’ .