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Why is a second Adar added on certain years?

by Rabbi Yosef Resnick


Library » Miscellaneous » The Jewish Calendar | Subscribe | What is RSS?


Let’s first examine when Pesach should be celebrated, and why.

There are two verses in the Torah that tell us when Pesach should be observed. Yet together, they seem to pose a slight contradiction.

In the book of Exodus1  the verse states that we should celebrate Pesach on the 14th day of Nissan.

Later, in Deuteronomy,2   the Torah states: “Guard (shamor) the month of spring (Chodesh haAviv3), and make Passover to the L-rd your G-d, because it was in the month of spring that the L-rd your G-d took you out of Egypt in the night.”

So we know two things about celebrating Passover:

a) It must be on the 14th of Nissan, and

b) it must be in the spring.

So where is the contradiction I promised you? First we need to take a look at the way the Jewish calendar is set up. The Jewish calendar is a lunar one, with each month (i.e. lunar cycle) consisting of (approximately) 29.5 days.

That means that the lunar year is 354 days. The Gregorian calendar is solar, with each year (solar cycle) lasting 365 days. So every year the Jewish calendar falls behind the solar calendar by eleven days.

The 14th of Nissan would gradually slip backwards through the seasons as the Gregorian calendar pulled ahead, until we would eventually be celebrating Passover in December!
If the Torah had said only that we must keep Passover on the 14th of Nissan, and hadn’t mentioned the spring, there would be no problem. It’s just that the 14th of Nissan would gradually slip backwards through the seasons as the Gregorian calendar pulled ahead, until we would eventually be celebrating Passover in December!

Since we know from the second verse that Passover must be in the spring, we need to find some way to keep this Yom Tov from ending up as a summer, fall, or winter holiday.

Rashi, the foremost Torah commentator, addresses this issue. He wonders, what exactly does it mean to “guard” the month of spring, as our second verse enjoins us to do? Rashi explains: “Before it comes, make sure it is fit for the spring, to offer in it the meal offering of the Omer. And if not, proclaim a Leap Year.”

The commentary known as Sforno, written by Rabbi Ovadia ben Yakov Sforno, explains Rashi’s solution in slightly more detail: “Guard with the utmost care that the month of Nissan should be in the spring, through making leap months and leap years, by means of which the lunar and solar months should be consistent.”

It is for this reason that we add a whole leap month to the Jewish calendar every few years. When the difference between the solar and lunar years adds up to about one month, we add a second month of Adar, called Adar Sheni (or Adar II), before Nissan.

In this way, we can play “catch-up” with the solar calendar, and continue to celebrate Passover in the spring, as the Torah tells us to do.

Which is a good thing if you think about it, because if Passover came a week after Chanukah, when would we have time to clean our houses? And spring cleaning just wouldn’t be the same without the search for Chametz!4


  • 1. 12:18.
  • 2. 15:1.
  • 3. The word “Aviv” literally refers to a stage in the ripening of the grain.
  • 4. Sources: HaSeder haAruch, by Rabbi Moshe Yakov Vinegarten. Yerushalayim, 1991. The Living Torah, by Rabbi Aryeh Kaplan. Moznaim Publishers, 1981.


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Torah is G–d’s teaching to man. In general terms, we refer to the Five Books of Moses as “The Torah.” But in truth, all Jewish beliefs and laws are part of the Torah.
Leap Year
Every 2-3 years an extra month is added to the Jewish calendar. Since the lunar year, which Jews follow, is 11 days shorter than the solar year, it is necessary to keep pace, so that holidays corresponding to certain seasons remain in sync. On a leap year, a second month of Adar is added.
Any leavened product which is produced from wheat, barley, rye, spelt or oats. This includes bread, cake, cereals, crackers, biscuits, yeast, pasta and whisky. It is forbidden for a Jew to possess or consume Chametz throughout Passover.
A Biblically mandated early-spring festival celebrating the Jewish exodus from Egypt in the year 1312 BCE.
An eight day mid-winter holiday marking: 1) The miraculous defeat of the mighty Syrian-Greek armies by the undermanned Maccabis in the year 140 BCE. 2) Upon their victory, the oil in the Menorah, sufficient fuel for one night only, burned for eight days and nights.
Acronym for Rabbi Shlomo Yitzchaki (1040-1105). Legendary French scholar who authored the fundemental and widely accepted "Rashi commentary" on the entire Bible and Talmud.
The twelfth month on the Jewish calendar. This month (which falls out approx. February-March), is the most joyous month on the calendar due to the holiday of Purim which is on the 14th and 15th of this month.
The first month of the Jewish calendar. This month, which falls out in early spring, is known for the holiday of Passover which starts on the 15th of Nissan.
Starting from the second day of Passover, we count forty-nine days. The fiftieth day is the holiday of Shavuot. This is called the “Counting of the Omer” because on the second day of Passover the barley “Omer” offering was offered in the Holy Temple, and we count forty-nine days from this offering. [Literally, "Omer" is a certain weight measure; the required amount of barley for this sacrifice.]
Yom Tov
Jewish Holiday.
1. The miraculous departure of the Israelites from Egyptian bondage in 1312 BCE. 2. The second of the Five Books of Moses. This book describes the aforementioned Exodus, the giving of the Torah, and the erection of the Tabernacle.
The fifth of the Five Books of Moses. This book is a record of the monologue which Moses spoke to the Israelites in the five weeks prior to his passing.
Passover. A Biblically mandated early-spring festival celebrating the Jewish exodus from Egypt in the year 1312 BCE.
It is forbidden to erase or deface the name of G-d. It is therefore customary to insert a dash in middle of G-d's name, allowing us to erase or discard the paper it is written on if necessary.