Jesus was put to death on Passover eve Nisan 14.

This was the first full moon following the vernal equinox.this year the vernal equinox is March 20.2016 The first full moon after March 20 is March 23 2016.

This is the day that Jehovah's Witnesses will have their annual memorial of Christs death event.

That is why those who celebrate Easter will be doing so on March 27 2016. The first Sunday following the paschal full moon.

All seems to be in order until I check the date for Passover this year and it is April 22 2016.

Can someone explain why there is almost a full month lag for Passover this year?

  • 1
    Related: judaism.stackexchange.com/q/68709/1713
    – Daniel
    Commented Feb 28, 2016 at 20:17
  • @Daniel hmm something just feels unsatisfying about that answer, no offense. Granted it's not exactly the same question. I think without mention of how the new year is decided it is incomplete. It used to be by observance of the moon and then the season. If the season hasn't changed to spring yet, they would intercalate manually, thus we have Adar I & II. The new Jewish calender, Hillel II's, calculates it. So it doesn't always agree with our observance. You got into that, but you don't have info on how Easter is arrived at differently. .
    – Joshua
    Commented Feb 29, 2016 at 11:55
  • @JoshuaBigbee right that question doesn't ask about the calculation of Easter. I am planning on adding a bit today about how intercalation worked prior to the set calendar. It turns out that the manual addition of a month wasn't as simple as that and Passover likely occasionally fell a month after the equinox even then.
    – Daniel
    Commented Feb 29, 2016 at 12:56
  • @JoshuaBigbee See my updated answer. I have included some bonus information that presents a scenario in which Passover is pushed to the second full moon after the equinox even during the period of manual intercalation.
    – Daniel
    Commented Feb 29, 2016 at 15:34
  • @Daniel I'll look, I hope my comment was constructive :)
    – Joshua
    Commented Feb 29, 2016 at 16:05

5 Answers 5


Jehovah's Witnesses time their Memorial based on the current apparent movements of the actual physical moon and sun, as observable from Jerusalem. This, they say, is what happened in first century Judaism. The rule is not exactly the first full moon following the equinox, but the result is very close to this.

Jews and Christians base Passover and Easter, respectively, on mathematical models of how the moon and sun move. These idealised models were calculated in the 4th century AD. They are somewhat out of step with the real moon and sun, used by JWs.

The result is that the assumed date of the Vernal Equinox has drifted later than the actual date. The earliest date Passover can now fall is March 26th. The Full Moon on March 23rd, 2016 is too early for this, and so Passover is based on the following Full Moon, in April. This drift is continuing, but very slowly. Passover was on March 26th in 2013, and will again be on March 26th in 2089, and then never again. After that March 27th is the earliest. The last ever March Passover, based on current arrangements, will be March 31st 3248. In 3411, Passover will fall in May for the first time.

In Christianity the situation is complicated by the fact that Western Christians have made adjustments to correct the drift of sun and moon dates, so that the idealised sun and moon correspond more accurately to the real ones. Eastern Orthodox Christians have not. The drift is such that the earliest the Paschal Full Moon can fall, according to the Eastern Church, is April 3rd. Just as for Jews, the March 23rd full moon this year is too early to be counted, and so it is the April Full Moon is regarded as the Paschal one.

Western Christians have made adjustments so that the earliest date the Paschal Full Moon can fall is March 21st, close to the real vernal equinox. Therefore the March 23rd Full Moon does count and so Easter Day is the following Sunday, March 27th.

Apart from the month, the actual assumed dates of full moons can vary by a day or two from the real ones for both Jews and Western Christians. For Eastern Christians the ideal full moon occurs 4 or 5 days later than for Western Christians.

So for 2016 there are full moons on March 23rd and April 22nd. The Jehovah's Witnesses Memorial is on March 23rd. Western Easter is the following Sunday, March 27th. Passover is the following full moon, April 22. The Eastern Orthodox model full moon is four days later than this, April 26th, and so Orthodox Easter is the Sunday after this, May 1st.

Fort the whole of this century if we divide the year AD by 19, and the remainder is 2, 10 or 13, then Passover will be about a month later than Western Easter. If the remainder is 2, 7, 10, 13 or 18 then the Eastern Easter will be 4 or 5 weeks later than the Western one. In other years, if the Full Moon is early in the week, Eastern and Western Easters coincide, but if later in the week the Eastern Easter is one week after the Western, as the 4 or 5 day discrepancy pushes the assumed full moon into the following week.

  • 1
    Could you please cite some sources in your answer? What you're saying is consistent with what I've been taught (though the drifting of the Vernal Equinox was new to me), but it would be nice to know for sure.
    – user32540
    Commented Mar 6, 2018 at 19:51
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    "Drifting of the Vernal Equinox" is called precession of the equinoxes. So, for example, the vernal equinox in the year of Christ's death in 30 CE would have been on March 23, while in 2018 the equinox falls on March 20.
    – SLM
    Commented Mar 6, 2018 at 20:57

The Christian method for calculating Easter is not the same as the Jewish for calculating Passover. This was settled in the fourth century in Council of Nicea. Christians use the Sunday after the first full moon after the spring equinox as the date for Easter. While the Jewish tradition maintains the lunar calender. A complete explanation is given in the Wilton Bulletin.

  • Welcome! Thanks for contributing. It wouldn't hurt to expand this answer a bit and include more from that article (or other sources), but this is a great start. If you haven't already done so, I hope you'll take a minute to take the tour and learn how this site is different from others. Commented Feb 28, 2016 at 22:24
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    That article doesn't explain why Easter occasionally falls out a month before Passover. It just says that it happens occasionally. See my answer on Mi Yodeya.
    – Daniel
    Commented Feb 29, 2016 at 2:45
  • Calendars are fun. I am glad that you pointed out the lunar calendar vs the Gregorian calendar. With the adjustments made to the Gregorian calendar and the alignment with a lunar (or Venus, or Jupiter, or any other body) calendar, it is difficult to get exact times pin pointed. Rhetorically speaking, it wasn't that long ago that sun dials were an acceptable form of keeping track of time. Depending on your altitude, the time isn't exactly the same everywhere. Tell your boss that the reason why you're late is because you use a sundial to tell time. Commented Feb 29, 2016 at 14:35
  • The Council of Nicea did not "settle" the calculation of Easter. It was worked out in practice, in a process that took centuries. All Nicea said was that the Jewish calendar would not be used to calculate it, and that everyone should celebrate on the same day, Commented Jul 15, 2021 at 0:56

In the Rabbinic Jewish calendar a synodic lunar month consists of 29 days, 12 hours, and 793 divisions. There are 1080 divisions in an hour. (Louis A Resnikoff, "Jewish Calendar Calculations", Scripta Mathematica 9,191-195(1943). This is the value from Ptolemy's Almagest and is equal to 29.530594 days. Two-hundred thirty-five synodic lunar months make up 19 solar years in the Rabbinic calendar. (Resnikoff). That means that 19 solar years consists of 6939.689622 days. Divided by 19, this gives an implied solar year of 365.2468 days. This is slightly longer than the mean time between two Spring equinoxes, which is currently 365.242374 days. (Wikipedia). So there is a slight solar drift in the Rabbinic calendar. The present-day Rabbinic calendar was developed in the period A.D. 700-950, though a late Jewish tradition gives a date in the 4th century. (Sacha Stern, Calendar and Community Oxford University Press, 2001.) Over the intervening centuries this solar error has accumulated to where, as davidlol wrote in his answer, the earliest that the Feast of Unleavened Bread can now fall in the Gregorian calendar is March 26th. The result is that, at the present day, the Feast of Unleavened Bread and Easter are in different lunar months in 3 years out of every 19. These are the 3rd, 11th, and 14th years of the Western Easter cycle, which correspond respectively to the 19th, 8th, and 11th years of the Jewish cycle. The year 2016 was the 3rd year of the Western Christian cycle and the 19th year of the Jewish cycle.

A "rectified" Jewish calendar has been proposed which would eliminate the slow solar drift in the Rabbinic calendar. It would include an occasional intercalation cycle of 11 years among the cycles of 19 years.

  • There are several articles entitles "Rectified Hebrew Calendar". Would you please edit your answer to copy and paste the relevant article, and perhaps point us to the bit that matters?
    – Lesley
    Commented Feb 21, 2021 at 17:08

Why are the dates for Passover and Easter almost a month apart this year? (2016)

It is because at times the Jewish lunar calendar has an extra month added to it, thus this discrepancy occurs at times.

The Jehovah's Witnesses time their Memorial as being based on the current apparent movements of the actual physical moon and sun, as observable from Jerusalem.

The Jewish lunar calendar has more fluctuations involved in its’ computations.

Here's Why Passover Is So Late This Year

Passover begins this Friday, later than usual and almost a month after the Christian celebration of Easter, which fell on March 27 this year.

The Jewish holiday falls on the same day in the Jewish calendar every year, but because that calendar is based on the lunar cycle, the celebration of Passover varies according to the Gregorian calendar.

In order to keep the Hebrew year aligned with the seasons of the solar calendar, the Jewish calendar regularly includes leap years that add an extra month—and 2016 is one of them. Leap years occur seven times in a 19-year cycle, and this year pushed Passover into late April.

The Jewish Passover does not always occur on the first full moon on or after the Spring Equinox!

First, some background information:

Our current 19-year intercalary cycle was instituted by Hillel II in the fourth century CE. The calendar is a lunisolar calendar which typically has 12 months. A normal year is 354 days, which is approximately 11.25 days shorter than the solar calendar. To correct for this, the Hebrew calendar has a leap year every 2 or 3 years for a total of 7 times every 19 years. In those leap years, instead of a single day (which we add to our solar calendar), an entire month is added.

Now your question:

According to Wikipedia, at the time when the calendar started, the earliest Passover (corresponding to the 16th year of the 19-year cycle) fell on the vernal equinox and Passover always fell on the first full moon following the equinox.

Over the centuries, there has been a very slight seasonal drift in the calendar (the average year is just over 6.5 minutes longer than the Gregorian calendar). As a result, the calendar has shifted about 7 and a half days later relative to the equinox. But since the months themselves cannot be shifted by a full week (since the new month is tied to the new moon) the result is that in certain leap-years, the leap-month which is supposed to correct for the drift is inserted a year earlier than it should have been to actually match the equinox. This currently happens in the 8th, 11th, and 19th years of the 19-year cycle. Basically, in those years, there has been one more leap year than there actually "should have been" between the fourth century and today.

As you mentioned, this year Passover is not on the first full moon following the vernal equinox. That is because, this year is the 19th year of the current 19-year cycle, which is one of the years where the leap-month is added "prematurely". At this point, there is not much concern about Passover occasionally falling out on the second full moon after the equinox. There is no requirement in the Torah that it fall on the first full moon. There is, however, a requirement that Passover must fall in the Spring (it is called the Spring Festival). If the current calendar were to be followed indefinitely, Passover would eventually fall in the summer due to continued seasonal drift. This would be problematic, but it is not of immediate concern because it would take millenia for this to happen. The hope is that the messiah will come well before then and re-introduce the court-based institution of the months and leap years.

Some bonus information:

You may have noticed that I mentioned that our current calendar was instituted in the fourth century. Of course, the time period that Christians are interested in occurred before this time. Prior to the establishment of the fixed (calculated) calendar, the leap years were determined by the courts. The main factors that the courts took into account was the relationship between Passover and the equinox. They needed to make sure that Passover always fell after the vernal equinox. In addition, however, they could consider other factors that affected the ability of the people living throughout Israel to properly observe the Pesach festival. If the winter rains had destroyed the roads and bridges (which would prevent people from far away from making the festival pilgrimage) or they had destroyed the ovens for roasting the paschal sacrifice, the courts could institute a leap year in order to allow an extra month for the roads and ovens to be fixed before the festival (see Rambam - Mishneh Torah, Kiddush HaChodesh, Chapter 4, Halakha 5).

In a year which was declared a leap-year for one of those reasons, it is entirely likely that such an additional month would push Passover to the second full moon following the equinox. So even before the set calendar and seasonal drift, it was possible for Passover to fall out not on the first full moon. I am not aware of how often this happened (if it ever actually happened at all), but it is most likely (in my opinion) that Passover did occur in the first full moon following the equinox (as it does in most years now and probably in almost all years back then) in the year Christians believe Jesus was killed . - Does Passover occur on the first full moon after the equinox?


The reason for the difference in dates has to do with misunderstanding the solar/lunar calculation of Ex. 12:2.

This month shall be unto you the beginning of months: it shall be the first month of the year to you.

How is that understood? Please note that verse refers to the lunar (months) and solar (year) measurements.

Year in Hebrew is shaneh. It means year as a division of time, of age, a revolution (return) of the sun. It has to first make a complete revolution to accurately mark the beginning of the months.

From Moses to Christ, it was known that the sun first had to have passed the spring equinox and then one looks for the new moon from which to count to the 14th day Passover (or as it too became muddled, the full moon of the 15th).

Here are quotes from Philo of Alexandria, a contemporary of Christ, on how they calculated the month and Passover.

THE THIRD FESTIVAL XXVI. (140) Following the order which we have adopted, we proceed to speak of the third festival, that of the new moon. First of all, because it is the beginning of the month, and the beginning, whether of number or of time, is honourable.

The new moon is the beginning of the month. Next comes Passover on the fourteenth of that month.

THE FOURTH FESTIVAL XXVII. (145) And after the feast of the new moon comes the fourth festival, that of the passover, which the Hebrews call pascha, on which the whole people offer sacrifice, beginning at noonday and continuing till evening.

So, what of the vernal equinox? How does that enter the picture?

I will first jump to Josephus who says this about the year and month calculation of the beginning of the year.

  1. In the month of Xanthicus, which is by us called Nisan, and is the beginning of our year, on the fourteenth day of the lunar month, when the sun is in Aries, (for in this month it was that we were delivered from bondage under the Egyptians,) the law ordained that we should every year slay that sacrifice which I before told you we slew when we came out of Egypt, and which was called the Passover; and so we do celebrate this passover in companies, leaving nothing of what we sacrifice till the day following. http://www.ccel.org/ccel/josephus/complete.ii.iv.x.html

And now back to Philo who defines the same mark (vernal equinox) as he describes the Fifth Festival of Unleavened Bread.

This month, being the seventh both in number and order [the original order until changed at Ex. 12:2], according to the revolutions of the sun, is the first in power; (151) on which account it is also called the first in the sacred scriptures [Ex. 12:2]. And the reason, as I imagine, is as follows. The vernal equinox is an imitation and representation of that beginning in accordance with which this world was created. Accordingly, every year, God reminds men of the creation of the world, and with this view puts forward the spring, in which season all plants flourish and bloom; (152) for which reason this is very correctly set down in the law as the first month, since, in a manner, it may be said to be an impression of the first beginning of all, being stamped by it as by an archetypal Seal. ... And this feast [of Unleavened Bread] is begun on the fifteenth day of the month, in the middle of the month, on the day on which the moon is full of light, in consequence of the providence of God taking care that there shall be no darkness on that day.

And see here and here in which the latter states: "But this Aristobulus also adds, that for the feast of the Passover it was necessary not only that the sun should pass the equinoctial segment, but the moon also."

Thus we learn that to properly calculate the first month the sun had to be in Aries, the sun had to pass through the Spring Equinox, and then you look for the new moon. They didn't measure the beginning of the year from only the first full moon after the Spring Equinox. The correct calculation that made sure the sun was in Aries (after the Spring Equinox) necessitates when the intercalary month was added. The sun was in Aries, then they looked for the new moon, and thus the full moon.

As centuries past, the way to count became more muddled. By the time of Constantine (325 CE), the accusation became that the Jews were observing two Passovers in one (solar) year. This happened because they failed to count the solar year properly.

For the OP example shown in 2016, we see this problem in operation. For JW, they only counted the first full moon of 3/23/16 as the day of their memorial. This means the solar/lunar calendar would still be measuring the previous year 2015. In 2015, Passover fell on 4/4/15. For 2015, the sun had passed the Spring Equinox, the first new moon observed, and the full moon was 4/4/15. In 2016, the sun had not passed the Spring Equinox to mark the start of observing the first new moon and thus the full moon. Instead 3/23/16 (and Sunday 3/27/16) was merely the first full moon after the Spring Equinox. In this way, they mistakenly observed two Passovers in one year.

So, that's the reason for the "lag" so called. It's not that Easter was particularly miscalculated in 2016, but rather the JW (and Christian) observance was based on how later Jewish calculations came into play, rather than how Christ would have done it.

PS. To clarify, Easter was observed in 2016 on the first Sunday 3/27 following that first full moon on 3/23.

The Jewish Passover was observed 4/22.

If you love irony sharpening irony, this is a great example. In other words, the answer remains the same, but it's the switch. In Christ's time they observed the Passover on the first full moon after the first new moon after the Spring Equinox. That meant the sun had passed the Spring Equinox (in Josephus' parlance, it was in Aries). That's the correct way to calculate and thus observe the death, burial, resurrection of Christ Jesus.

  • Not to beat a dead horse but your answer still contends that JWs erred in there calculation of the date of Jesus’ death in 2016. They did not. JWs do not observe Passover but do have a special worship service each year to commemorate the sacrificial death of Christ. If JWs were in error in 2016 then all of western Christianity was also in error with Easter falling on 3-27-16.
    – 007
    Commented Mar 2, 2018 at 12:59
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    @SLM Josephus in your quote seems to say the full moon when the sun is in Aries. If they celebrated on the full moon after the new moon after the equinox the celebration would often be the full moon when the sun was in Taurus, woulfnt it? The Josephus quote doesnt seem yo support the fm after the nm after the ewuinox theory.
    – davidlol
    Commented Mar 4, 2018 at 9:03
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    @SLM I have never heard that Nisan 1st must be after the Spring Equinox. Could you find a source that specifically says this? The quote from Josephus documented that it was in Aries that year, but doesn't necessarily mean it was a rule.
    – user32540
    Commented Mar 6, 2018 at 16:17
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    @SLM All of these quotes definitely prove that the Passover (Nisan 14th) is after the equinox, but don't discuss the claim that Nisan 1st is always after the equinox. Wikipedia says that Nisan 1st must be on the New Moon within 15 days of the equinox (either before or after). The downvote is for lack of evidence, not for some personal dislike.
    – user32540
    Commented Mar 6, 2018 at 19:43
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    The scripture doesn't discuss when Nisan occurs, and the quote from Aristobulus is the only one that discusses the equinox in reference to the first day of Nisan (the rest are only about the Passover). It says that those who place the equinox in the first month "commit no slight or common blunder". The first day of Nisan would have to be before the equinox for that to happen.
    – user32540
    Commented Mar 7, 2018 at 0:04

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