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Before I explain about the Jewish Calendar, I have a simple little quiz for you to take.

All you have to do is get four questions out of 10 right. This will put you in the mood for learning about the Jewish Calendar.


1) How long did the Hundred Years’ War last?

2) Which country makes Panama hats?

3) From which animal do we get catgut?

4) In which month do Russians celebrate the October Revolution?

5) What is a camel’s hair brush made of?

6) The Canary Islands in the Pacific are named after what animal?

7) What was King George VI’s first name?

8) What color is a purple finch?

9) Where are Chinese gooseberries from?

10) What is the color of the black box in a commercial airplane?

Remember, you need only 4 correct answers to pass. Check your answers below …

ANSWERS TO QUIZ 1) How long did the Hundred Years War last? 116 years 2) Which country makes Panama hats? Ecuador 3) From which animal do we get catgut? Sheep and Horses 4) In which month do Russians celebrate the October Revolution? November 5) What is a camel’s hair brush made of? Squirrel fur 6) The Canary Islands in the Pacific are named after what animal? Dogs 7) What was King George VI’s first name? Albert 8) What color is a purple finch? Crimson 9) Where are Chinese gooseberries from? New Zealand 10) What is the color of the black box in a commercial airplane? Orange (of course) What do you mean, you failed?

The High Holidays, Sukkot, Chanukah, Purim, Passover, and Shavuot are always celebrated on their specific dates on the Jewish calendar. (For example, Rosh Hashanah is always celebrated on 1–2 Tishrei, and Passover always begins on 15 Nisan.) So the holidays are never late or early. They just come out differently on the English Calendar.

Other notable occasions that follow the Jewish calendar are birthdays, yahrzeits, bar mitzvahs, and bat mitzvahs.

The Jewish Calendar and how it works was Given to Moses at the Exodus. This is what Jews believe about the entire Torah.

Exactly two weeks before the Exodus from Egypt, G‑d told Moses and Aaron: “This month [Nisan] shall be for you the head of the months, setting into motion the Jewish calendar and its unique format. In fact, this was the very first commandment G‑d gave to Moses.

It Follows the Lunar Cycle, But Is Still Aligned with the Seasons

Unlike the Gregorian calendar, which follows the solar cycle (of about 365.25 days), the Jewish calendar follows the lunar cycle, which means that the year is comprised of 12 lunar months (of approximately 29.5 days each).

Nevertheless, the Jewish calendar is not solely lunar. Due to the 11-day discrepancy between the solar year (365 days) and the lunar year (29.5 × 12 = 354), lunar calendar dates are not tied to the seasons. If a certain day occurs this year in the spring, in a few years it will regress to the winter, and so on.

On the Jewish calendar, referred to as a lunisolar calendar, the dates are aligned with the seasons. For example, Passover must be celebrated in the spring. In order to prevent a regression, every two or three years a thirteenth month is added (more on that below).

Here is a list of the Jewish months and their important dates:

Jewish Month Approximate Secular Date -This Month’s Special Dates

Nisan March–April Passover

Iyar April–May Lag B’Omer

Sivan May–June Shavuot

Tammuz June–July

Menachem Av (also known as Av) July–August Tisha B’Av

Elul August–September

Tishrei September–October The High Holidays (Rosh Hashanah and Yom Kippur), Sukkot, Shemini Atzeret and Simchat Torah

Marcheshvan (also known as Cheshvan) October–November

Kislev November–December Chanukah

Tevet December–January Conclusion of Chanukah

Shevat January–February Tu B’Shevat

Adar February–March Purim

Months Are Either 29 or 30 Days

In the Gregorian calendar, most months are either 30 or 31 days (because 365 ÷ 12 = 30.4). In the Jewish calendar, since the lunar cycle is about 29.5 days, all months are either 29 days (known as “missing” months) or 30 days (known as “complete” months).

Most months have a set number of days (Nisan—30, Iyar—29, Sivan—30, Tammuz—29, and so on). There are two exceptions: Marcheshvan and Kislev can be either 29 or 30 days (see below).

Leap Years Have Thirteen Months

In the Gregorian calendar, every four years an extra day is added, creating a leap year—a year with 366 days instead of 365 Like this year 2020. In the Jewish calendar, however, leap years have an additional month.

The Torah specifies that Passover must be celebrated in the spring, and Sukkot during autumn. This poses a problem, as the lunar year is eleven days short of the solar year, and any given date will potentially regress from one season to the next.

In order for the festivals to retain their positions relative to the seasons, an adjustment must be made to enable the lunar calendar to maintain harmony with the solar cycle. To do so, years are grouped into 19-year cycles. In the 3rd, 6th, 8th, 11th, 14th, 17th, and 19th year of every 19-year cycle, another month (Adar) is added. Such a year is called “shanah m’uberet,” literally “a pregnant year.”. If it were 7 out of 21 then it would be obviously every third year we would have a leap year. Since it is 7 out of 19, it is a little more often than every third year, being a leap year.

Therefore a Year Can Be Between 353 and 385 Days Long

The months of Marcheshvan and Kislev are variable. In any given year they can both be 29 days; they can both be 30 days, or Marcheshvan can be 29 days while Kislev is 30.

Based on this, any given year can contain either 353, 354, or 355 days (or in a leap year: 383, 384, or 385 days). When both months are 29 days, the year is known as chaseirah (missing); when both are 30, the year is shleimah (complete); and when Marcheshvan is 29 days and Kislev is 30, the year is k’sidrah (regular, meaning these two months follow the alternating pattern of the rest of the months).

The First Month Is Halfway Through the Year

Nisan is the first month on the Jewish calendar. Before the Jews left Egypt, on the first day of the month of Nisan, G‑d told Moses and Aaron: “This month shall be for you the head of the months.” Thus the peculiarity of the Jewish calendar: The year begins on Rosh Hashanah, the first day of the month of Tishrei, but Tishrei is not the first month. Rosh Hashanah is actually referred to in the Torah as “the first day of the seventh month.

New Months Were Originally Determined Based on Lunar Sightings

Originally there was no fixed calendar. Each month, the Sanhedrin—the rabbinical supreme court—would determine whether that month would contain 29 or 30 days, depending on when the following month’s new moon was first sighted.

On the 30th day of every month, the Sanhedrin began accepting witnesses who claimed they had spotted the new moon the previous evening. If the witnesses would pass the court’s rigorous interrogation, the Sanhedrin would “sanctify” the new month, proclaiming that day the first of the month. The previous month was now retroactively determined to have had only 29 days.

If no witnesses came on the thirtieth day, then the next day, the thirty-first day, was automatically declared the first day of the new month, retroactively rendering the previous month a “complete” month of 30 days.

The Calendar We Use Today Was Established in the 4th Century CE

In the 4th century CE the sage Hillel II foresaw the disbandment of the Sanhedrin, and understood that we would no longer be able to follow a Sanhedrin-based calendar. So he and his rabbinical court established the perpetual calendar which we follow today.

When Hillel established the perpetual calendar, he sanctified every new month until Moshiach will come and re-establish the Sanhedrin.

Outside Israel, Holidays Have an Extra Day

Originally, when there was no fixed calendar, there was no way to determine the exact day of a coming festival in advance. This was because every festival falls on a particular day of a month, and the month would begin only when the new moon of that month was sighted.

Once the Sanhedrin had determined that a new moon had been sighted, messengers were dispatched to Babylonia and other far-flung Jewish settlements to relay this information to them. Since news traveled a lot slower in those days, many communities outside of Israel would not know when the new month had begun in time to celebrate the festival on a proper day. To cover both possibilities, they would celebrate every holiday for two days: the day the holiday would be if the previous month had 29 days, and the day it would be if there were 30 days

The First Day of Each Month Is a Minor Holiday

The first day of each month (and sometimes, the last day of the previous month—see below) is known as Rosh Chodesh (lit., “head of the month”). Special prayers are added to the daily services, and we wish each other “Chodesh Tov,” a good month.

Since the 30th day of the month was always potentially Rosh Chodesh (see above), whenever a month has 30 days, the last day is observed as Rosh Chodesh together with the first of the following month.

However, if a month has only 29 days, then the Rosh Chodesh of the following month will be only one day—the first of the month.

The First Year Was Only Five Days Long

The years of the Jewish calendar are calculated from the creation of the world. Hence, in 2020, it is presently 5780 years since Creation.

However, Rosh Hashanah, the Jewish New Year, is celebrated on the day Adam was created, which was really the sixth day of creation. Creation itself began five days earlier, on the 25th day of the month of Elul.

When we give the number of 5781, we actually mean that it is presently 5780 years and five days since Creation, as those initial five days are considered Year 1, and Adam’s creation marked the beginning of Year 2. The New Year will be 5782.


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Yehuda Lave is an internationally known speaker, lecturer, journalist, author, psychologist, rabbi, spiritual teacher, and life coach, with degrees in business, psychology, Jewish and American Law. His motto: Remember, it only takes a moment to change your life. Learn to have all the joy in your life that you deserve!!! Subscribe to his free daily blog by sending an email to [email protected]