Why Passover And Easter Are A Month Apart This Year

Well, almost a month.

It seemed to me, though I'd never actually looked it up, that Easter and Passover were generally pretty close together and it had something to do with the last supper being a seder.

 But I noticed this year that Easter is March 27 and Passover doesn't begin until April 22.

 I got an answer - but I decided to double check and the other answers were overlapping, but not quite exactly the same. So here are three sources. This one is about why they are both generally around the same time, from My Jewish Learning:

"First, their inviolable matrix is spring. In each case, the calendar is adjusted to ensure that the holiday is celebrated early in the spring. For the church, which believed that the resurrection took place on a Sunday, the First Council of Nicaea in 325 determined that Easter should always fall on the first Sunday after the first full moon following the vernal equinox. In consequence, Easter remained without a fixed date but proximate to the full moon, which coincided with the start of Passover on the 15th of Nissan. 

By the same token, the rabbis understood the verse “You go free on this day, in the month of Aviv” (Exodus 13:4) to restrict Passover to early spring — that is in a transitional month when the winter rains end and the weather turns mild. The word “Aviv” actually means fresh ears of barley.   

Moreover, since the Torah had stipulated that the month in which the exodus from Egypt occurred should mark the start of a new year (Exodus 12:2), the end of the prior year was subject to periodic extension in order to keep the Jewish lunar calendar in sync with the solar year. Thus, if the barley in the fields or the fruit on the trees had not ripened sufficiently for bringing the omer [the first barley sheaf, which was donated to the Temple] or the first fruits to the Temple, the arrival of Passover could be delayed by declaring a leap year and doubling the final month of Adar (Tosefta Sanhedrin 2:2). In short, Easter and Passover were destined to coincide time and again. .  ."

Here's the first one I found that looked at why the two were not so close together this year.  It's from Studies In The Word, and has the dubious title of "Why the Jewish calendar will be incorrect in 2016":

In trying to follow Exodus 12:2, Exodus 13:3-4, 7-10, and Numbers 9:2-3, Judaism [I didn't know that Judaism could speak] says that Passover, which they celebrate on Nisan 15 rather than on Nisan 14, must not fall before the northern hemisphere spring equinox (Tekufot Nisan). The spring equinox currently occurs each year on March 20th or 21st and is that time when day and night are of approximately equal length. The spring equinox establishes the first day of spring. It is a solar, not a lunar, phenomenon. 

But current Jewish calendar procedures periodically conflict with the use of the equinox to establish the first month of the religious year: 

In 2016, Nisan 14 (Passover) can fall on March 22, the first opportunity for the 14th day of a Biblical month to occur after the equinox. But the Jewish calendar sets Nisan 14 at April 22nd. Why? Because the Jewish year 5776 (the spring months of 2016 fall within the Jewish year 5776) happens to be the 19th year of the 19-year calendar cycle and is then, by Judaic definition, a leap year (the 13th month must be added). This forces the first month to begin one month later than it normally would. Unfortunately, their calendar leap year tradition is so rigid that they fail to follow what we agree is the correct interpretation of the scriptures listed above, that God gave them, which strongly imply that the Passover must be kept at the first opportunity on or after the spring equinox. 

What allows them to ignore their own calendar rules? One reason they feel free to adjust the calendar to their liking is because Leviticus 23:2 and 4 are interpreted by Jewish Oral Law as saying that the people are allowed to keep the Holy Days on whatever day is most convenient.

Another site I looked at explained why Easter and Passover were several weeks apart in 2014 - which shouldn't be related to a 19 year cycle if 2016 is on that cycle.  Part of this explanation comes from an astronomer:

"The Last Supper was indeed the Passover; thus Holy Thursday, in the year that Christ was crucified, fell on Passover. That made Easter, the day that Christ rose from the dead, the Sunday after Passover. 

Because Christians in different areas were celebrating Easter on different days, the Council of Nicaea, in A.D. 325, established a formula for calculating the date of Easter. That formula was designed to place Easter at the same point in the astronomical cycle every year; if followed, it would always place Easter on a Sunday after Passover. And indeed, that formula is still followed today. 

Why, then, will Jews celebrate Passover beginning on April 19, 2008, while Western Christians will celebrate Easter on March 23? 

The answer, as William H. Jefferys, the Harlan J. Smith Centennial Professor of Astronomy (Emeritus) at the University of Texas at Austin, explains, is that, since the standardization of the Hebrew calendar in the fourth century A.D., "actual observations of celestial events no longer played a part in the determination of the date of Passover." Thus, "the rule for Passover, which was originally intended to track the vernal equinox, has gotten a few days off." 

The same thing has happened with the Eastern Orthodox calculation of the date of Easter. Because the Eastern Orthodox still use the astronomically incorrect Julian calendar, rather than the Gregorian calendar that was adopted in the West in 1582, the Orthodox will celebrate Easter this year on April 27. 

With the adoption of the Gregorian calendar, the West brought the calculation of Easter back into sync with the astronomical calendar. In other words, the Western date of Easter is the most closely aligned to the astronomical cycles on which the date of Passover is supposed to be based."

This last one  "the rule for Passover . . . has gotten a few days off" but that doesn't explain why it was three weeks off in 2008 and is again that far off in 2016, which the second reference says is due to the Jewish calendar leap year.

I've quoted a little more than I normally would because there are lots of nuggets and I don't think I could summarize as neatly as the writers did.