Christian Churches of God

Why Is Passover So Late in 1997? (No. 239)

(Edition 1.0 19980217-19980217)

This article was published in the Jewish Bible Quarterly, Volume 25, No. 1, 1997 and is reprinted with permission. The Jewish Bible Association maintains a website at


Christian Churches of God



(Copyright ã 1997 Jewish Bible Association)

Published with permission of Executive Secretary, Jewish Bible Association

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(Saul Leeman is a retired Rabbi residing in Providence, R.I.)

Observe the month of aviv and offer a
Passover sacrifice to the Lord your God

Reading this verse in Deuteronomy 16:1 along with the relevant rabbinic literature, one would be justified in assuming that the Torah intended that the festival should occur, as it most often does, during the first month of spring season. This year (5757), however, it fails to do so. In order fully to understand the delay in the arrival of our spring festival, certain questions must be asked:

Why is Pesach so late this year?

Pesach is so late this year (April 22) because this is a leap year in the Jewish calendar with a thirteenth month intercalcalated. In every 19-year cycle there are 7 leap years: the 3rd, 6th, 8th, 11th, 14th, 17th, and 19th.

Yes, I know that. But in the course of the past 10 years or so, there have been a number of leap years, and yet I don't recall any Pesach being as late as this one.

That is because this is the 19th year of the cycle, a leap year that occurs after only a two-year interval following the preceding leap year. The same is true (and even more so) regarding the 8th year of the cycle. Thus there are these two years in every cycle when Pesach is late in the spring. In 1967 (an "8th year") Pesach fell on April 25, the latest it has been so far.

You say, "so far." Does that mean that Pesach can be even later than April 25?

Yes, indeed -- and this is the major problem of the Jewish calendar; i.e., that it is based on a calculation of the solar year that is inaccurate by about 6½ minutes. It is this inaccuracy that moves Pesach in the direction of the summer at the rate of almost a full day every 200 years, amounting to about 4½ days every 1,000 years. This means that in about 1,000 years hence, Pesach will be celebrated as late as May 1, and 8,000 years hence, it will be as late as June 1.

Can this be corrected?

This can be corrected only through calendar reform based on a recalculation of the calendar structure

You say that calendar reform will eventually be necessary. Has there ever been such a thing in recent history?

Yes, there has. In 1582 the Julian calendar, which had been in force since 46 BCE, was replaced by the Gregorian calendar. The Julian calendar, instituted by Julius Caesar, was based on a calculation that reckoned the length of the solar year at 365 days and 6 hours, when in reality it is about 11¼ minutes shorter.

This difference accumulated to an error of about 3 days every 400 years (or 7½ days every 1,000 years). As a result, by the 16th century, the vernal equinox retrograded to March 11. To restore it to its correct date, Pope Gregory XIII declared that the day following October 4 would not be October 5 but October 15. By this declaration, he restored the vernal equinox to March 21, the date at which it was in the year 325 CE when the Council of Nicea (in order to divorce Easter from Pesach) decreed that the formula for setting the date of Easter would be "the first Sunday after the first full moon on or after the vernal equinox."

Note that it was his concern for the proper Easter date that motivated the Pope's calendar reform.

Having eliminated the accumulated error of 10 days, the Gregorian calendar had also to provide that no such regression year should re-occur. This is accomplished by decreeing that the century years should not be a leap year except when it is divisible by 400. As a result of this provision, the years 1700, 1800, and 1900 -- leap years in the Julian calendar -- were not leap years in the Gregorian calendar. The difference between the two is now 13 days. In the year 2100, the difference will be 14 days.

But Jewish religious practice has no connection with the solar calendar. Aren’t all Jewish observances based on the lunar calendar?

Not exactly. There are two observances that are linked to the solar calendar. One of them is tal umatar, the prayer for dew and rain. The Talmud calls for the recitation of this prayer to begin 60 days after the autumnal equinox and to continue until Pesach. The prayerbook, however, fixes tal umatar day on December 5 -- 73 days after the equinox (September 23). This discrepancy of 13 days is the difference between the Julian and Gregorian calendars, and this differential continues to grow at the rate of 7½ days every 1,000 years.

With tal umatar day moving in the direction of Pesach at the rate of 7½ days every 1,000 years, the former will eventually overtake the latter in about 35,000 years. Long before that, however, the Pesach date will have to be adjusted, and thus the tal umatar problem too, will find its solution.

In Israel there is much less "alarm" regarding this problem because in the Holy Land the season of tal umatar starts in the first week of Heshvan and is not directly linked to the solar calendar at all (See Bab. Talmud, Taanit 10a).

You said that there were "two observances" linked to the solar calendar. What is the other one?

The other one is Birkat ha-Hammah -- the Blessing of the Sun, a benediction recited on the occasion of the vernal equinox once every 28 years when, according to traditions, the earth returns to the same position in relation to the sun that it occupied at the time of Creation.. It is always recited on a Wednesday (the day on which the sun was created). Its most recent recitation was on April 8, 1981; its next occurrence will be on April 8, 2009. That this is astronomically meaningless was particularly impressed upon us when the Blessing of the Sun took place on April 8, 1953 when we were then "celebrating the vernal equinox and inaugurating the Spring" -- on the 23 of Nisan, eight days after the advent of Pesach!

When the necessary calendar reform is accomplished, Birkat ha-Hammah will also fall into place. The "reform" will surely provide that Pesach will always fall on the first full moon of spring (not the second full moon as is the case this year) and Birkat ha-Hammah will be fixed to occur on the first Wednesday of Spring.

When was our present Jewish calendar instituted and by whom?

The Jewish calendar, as we have it today, was instituted by the Patriarch Hillel II, circa 359 CE.

Why is it based on a 19-year cycle?

Because the basic formula of the Jewish calendar is following 19 solar years = 235 lunar months (19 ordinary lunar years +7 additional lunar months). The Greeks called this the Metonic Cycle.

Does this mean that every 19 years the civil date (Gregorian) and the "Jewish date " coincide?

Yes, every 19 years they either coincide exactly or deviate by one day.

How many days are there in the Jewish calendar?

It varies. In an ordinary year (non-leap year) there are 353 days (defective), 354 days (regular), or 355 (excessive). Similarly in a leap year there are 383, 384, or 385 days.

What is the reason for this?

The reason is a religious one. The basic [lo 'adu rosh] is that Rosh Hashanah must not fall on a Sunday, Wednesday, or Friday. If Rosh Hashanah fell on a Wednesday or Friday, Yom Kippur would precede or follow the Sabbath, resulting in a situation that would involve hardship in its observance. If Rosh Hashanah fell on a Sunday, Hoshanah Rabbah would fall on the Sabbath and would call for the elimination of certain rituals which the pharisaic rabbis did not want to forgo.

Therefore a built-in flexibility was necessary whereby, if Rosh Hashanah were to fall on any of these three days, it would be postponed to the following day.

Thus, in a regular year (354 days), the months alternate between 30 and 29 days. In a defective year (353 days), the months of Heshvan and Kislev each has 29 days. In an excessive year (355 days), Heshvan and Kislev each have 30 days.

What was the procedure before the Patriarch Hillel II instituted the present fixed Jewish calendar?

Before that date, we had an unfixed "living" calendar. The new moon was determined by observation. Witnesses would come to Jerusalern to testify that they had seen it. If, after interrogation, the Beth Din was convinced of the validity of their testimony, the New Moon was sanctified, and Rosh Hodesh was declared. The Beth Din sat in readiness to receive witnesses only on "day number 30" of the outgoing month to determine whether that very day should be declared as "day number one" of the incoming month. If such a determination was not made on that day, the next day automatically (with or without witnesses) became Rosh Hodesh, because the month consists of not less than 29 nor more than 30 days. (See Mishnah Rosh Hashanah, Chapters 1-2).

Once the New Moon was sanctified, the news was then proclaimed throughout the length and breadth of the Holy Land.

What about the Jews outside of the Holy Land? How was the message transmitted to them?

That is a good question. Often, due to the difficulties of communication, the message did not arrive on time, and this thrust the Jews outside of Palestine into a serious religious quandary. For instance, when it came to observe Pesach, they had to speculate whether the previous month consisted of 29 or 30 days. If 29, then Pesach would be on a certain date; if 30, Pesach would be on the following day. What to do? To resolve the dilemma, they determined to "play it safe" and to observe the Yom Tov on both days. The same is true of Shavuoth and Sukkoth. Therefore, we Diaspora Jews (with the exception of our Reform brethren) have five more yom tov days per year than do the Jews of Israel.

What about Rosh Hashanah?

Rosh Hashanah is observed for two days in Israel also.

So much for the New Moon procedure before the calendar was fixed. Now tell me how were leap years determined before the fixed calendar?

Here, too, it was a living situation where the rabbis would deliberate before declaring the month of Nisan to consider whether or not the signs of spring have arrived (end of rainy season, ripening of grain, equinoctial considerations, etc.). If the spring seemed to be delayed, then a Second Adar was intercalated and the year became a leap year (See Bab. Talmud Sanhedrin 11 a & b).

Why was it found necessary to introduce the flxed calendar?

Because the patriarchate in the Holy Land no longer enjoyed its position of primacy and because the Roman government restricted the freedom of the Sanhedrin to act in these matters.

The Jewish calendar doesn't seem to be either lunar or solar. What would you call it?

It is a luni-solar calendar, the months being reckoned according to the moon and the year according to the sun.

You have already indicated that its calculation of the solar year deviates by about 6½ minutes from the true astronomical year. What about its calculation of the lunar month?

Here it is as accurate as it can possibly be. The Jewish calendar calculates the month at 29 days, 12 hours, 44 minutes, and 3.33 seconds -- a deviation from the true astronomical month of less than one half of a second.

To return now to what you have characterized as the "major problem" of the Jewish calendar -- how long will it take before Pesach occurs on June 21 and will, therefore, no longer be in the spring?

About 12,500 years.

Isn't it, then, too early now to worry about calendar reform?

Well, it certainly is not too early to think about it.

How will this calendar reform be carried out?

There are two ways: One a natural one, the other a supernatural. In one case, there would be a worldwide synod representing all factions of Jewry that would arrive at an agreement as to how and when to revise the calendar. In the other case, Elijah will come and settle the matter for us.

I note that you do not specify which of the alternatives you consider to be the natural and which the supernatural. But, in your view, which of the two eventualities is more likely to occur?

We'll just have to wait and see.