Understanding the Jewish Calendar

I. The Day

The Jewish day does not begin and end at midnight as does the secular calendar day. Midnight is not a distinguishable astronomic event. In the era before the modern clock, a specific hour of the night could not be precisely known. . . This meant that the day had to be reckoned either from the beginning of night or the beginning of day.

In Jewish time, the day begins with the onset of night (the appearance of the stars) followed by the morning (which technically begins with the appearance of the North Star). According to some Jewish teachers, night and morning begin with sunset and sunrise respectively. For that is how the Torah describes it: "And there was evening and there was morning, the first day."

For this reason, the Sabbath begins on Friday night and ends with the appearance of the stars on Saturday night. The same is true for the major holidays. . . Beginning the day with the night is, in a sense, a metaphor of life itself. Life begins in the darkness of the womb, then bursts into the brightness of the light and eventually settles into the darkness of the grave.

(Maurice Lamm)

II. The Week

In general, units of time can be divided into two categories. One category contains the units that measure something objective and observable, typically the movements of astrological objects. A day, for example, is the length of time it takes our planet to complete one rotation with respect to the sun. The second category is much more fun: totally random, basically meaningless divisions of time that were created out of a combination of superstition, incorrect science, and the need for greater precision in timing.

The seven-day week is in the latter category. There’s no good reason for it, and yet, it’s constant to almost every single culture. (Dan Nosowitz)

Jews count the week from Sabbath to Sabbath. The Sabbath is the crown of the week; the crown of Jewish Holy Days; the crown of the Jewish spirit; the crown of the Jewish imagination.

It is so rooted in the human condition that no matter how many societies have tried to uproot it, they could not. Some have simply moved the day: Christians to Sunday, Muslims to Friday. The Sabbath stamps its mark on the individual, on the nation, on the week.

All weekdays lead to the Sabbath. In fact, the days do not have names, only numbers, and these numbers all look to number seven, anticipating the arrival of the seventh day, the Sabbath, Shabbat. (Maurice Lamm)

III. The Month

Rosh Chodesh — which literally means “head of the month” — is the minor holiday that marks the beginning of every Hebrew month. The Jewish calendar, which combines both lunar and solar aspects, has 12 months (and 13 in leap years); half of these months are 30 days long and half are 29 days.

Originally, there was not a set calendar for Jewish months. Instead, the Sanhedrin (an ancient court) would declare a new month after receiving the testimony of two reliable witnesses reporting that they had seen the new moon. Then the message was spread throughout Israel and Babylonia via small fires on hilltops. When a new moon was announced, someone would go to the top of the Mount of Olives in Jerusalem with a long pole of wood. He would set the end of his pole on fire and wave it around until he could see someone on another hilltop waving his own pole. The second person waved his pole until he could see a third person waving, and so on until the message reached Babylonia. (My Jewish Learning)

IV. The Year

Jews count the months by the moon; western civilization patterns its calendar after the sun. That presents a dilemma. The moon travels more slowly than the sun -- by approximately 48 minutes a day. At the beginning of the lunar month, she sets in the west shortly after sunset, and each day 40 to 45 minutes later. She continues to lag further and further behind the sun (each lunar month being 29-1/2 days) until, at the end of 12 lunar months, the year of the moon is 11 days shorter than the year of the sun, every three years losing a full month of time.

This introduces a special predicament for the religious calendar: Passover needs to be celebrated at the vernal equinox -- springtime and harvest are its natural hallmarks, the resuscitation of nature coinciding with the redemption of the people. But, if the lunar calendar loses a month every three years, Passover would move further each year and fall successively in every season of the year. That is exactly what happens to the Muslim festival of Ramadan.

The sages ingeniously devised a perpetual calendar that would keep the holidays in the right season.

The teachers of the Talmud made the adjustment by adding seven leap months (called "Second Adar") in the course of each 19-year cycle, and thereby ingeniously devised a perpetual calendar that would keep the holidays in the approximate season for which they were originally conceived. (Maurice Lamm)

V. Calendar Years: Anno Mundi, BCE and CE

When Christianity rose to dominance in the western world, it began to date history from the birth of its own "king," later according to the Gregorian calendar. Hence, history was divided into BC and AD, before the advent of the king's birth and in the "year of the lord." Judaism could not consent to divide history along these lines.

Only one occurrence could serve as a beginning for history: the beginning of history. Judaism determined to count the years of the calendar on a universal scale -- from the creation of the universe. But exactly how old is the earth? Even scientists with their most advanced and exacting instrumentation are sure of only one answer: there can be no precision in this matter. The only method for the Sages was to count the years according to the literal account of creation in the Bible itself. [Note: by this count, the current secular year 2019 corresponds to the Jewish year 5779]

But this presented a problem: Jews everywhere were a minority and, while they could count time according to their view, they were living in an alien world where the overwhelming majority differed in this common legal practice. Jews, who resided over the face of the earth, could not ignore the way the world keeps time, the basis of a human being's daily life.

Therefore the Jewish community needed to accommodate its secular calendar to global usage.

As a result, it had to live its secular life according to "the nations" and to divide global history according to the exact dates of the Gregorian calendar. But it could not accommodate itself according to the Christo-centric terms of the historical divide -- BC and AD -- and referred to them instead as BCE, Before the Common Era, and CE, the Common Era.

The Jewish religious calendar, however, makes no recognition of this secular device, retains its universal format, and continues to count its years on a universal scale -- from the beginning of creation. (Maurice Lamm)

VI. When Does the Jewish Year Start?

Note: In Torah, the first month of the year is Nisan, the spring month in which Pesach/Passover falls

Note: In Torah, Rosh Hashanah is the first day of the seventh month and not the new year