Saturday, March 22, 2008

Easter Lunacy

This year is remarkable. The Christian holiday of Easter comes the earliest that it will come in our lifetimes - on March 23. It last came this early in 1913, and will not be this early again until 2160. Why is Easter so early? And why does it move around the calendar like it does? When I was a child, I looked at a calendar of 1953 and found Easter in the first week of April. So the next year I expected it again in the first week of April, but found by surprise that it was two weeks later, on April 18.

It is because Easter is based on the Moon as well as the Sun. The date of Easter is based on Passover, which occurs in the first Jewish month of the spring, on Nisan 15, the date of the full moon. It was decided to put Easter as the first Sunday past the first full moon after the March equinox. Instead of basing it directly on the Jewish calendar, for example, the first Sunday on or after Nisan 15, a new algorithm was developed, involving creating a mathematical model of the Moon called the Paschal full moon, and saying that Easter is the Sunday after that (if it is on Sunday, it's the next Sunday). The calculation of this moon involves calculating the Golden Number and the epact; the details can be found, for example, at Web Exhibits.

Since Easter is based on the Moon, one would expect a lot of lunacy with respect to this celebration. And sure enough there is. The very idea of holding Easter on a date that jumps from year to year in the calendar that we use in our everyday life can cause considerable disruption. This year, it is so early that it impinged on St. Patrick's Day. Most places celebrated it as usual, but the Catholic Church saw fit not to celebrate it because of it being in holy week. In many places it is cold this early, and some places may have weather more suitable for Christmas. Stores usually use holidays to promote their items, but there is no really good holiday between this year's Easter and Mother's Day this year, and April Fool's Day and Tax Day (April 15) just won't do.

Further, there is a lot of nonsense on the web about Easter. For example, in the Monticello, Indiana, Herald Journal, there appears this excerpt from Jerry Whybrew:

He said to them, "It is not for you to know the times or dates the Father has set by his own authority." Acts 1:7 Apparently, Easter day falls this year earlier than it has since 1913. It will be 2060 before it falls this early again. This is a very early Easter. Probably, if most of us would have our own way, we would move Easter later a few weeks when it would be a little warmer, flowers would be budding, and spring would be in full swing. But we aren't in control, and God has a purpose and a time for each and every event and situation in life. We can never expect to out-guess God. Life begins and life ends, and God is in control.

First of all, this person doesn't have control of his life. God does. The danger with supposing the existence of such a God is that the role of God could be filled by an actual person, and when it is, it is usually filled by a dictator. Next, he also says the date of Easter is one of those things we can't control. Not so. It is human beings, at the Nicene Council and other places that decided on the golden number-epact rule for Easter. There is nothing magical about it, and it doesn't even coincide with the Jewish feast of Passover or the actual full Moon. It can be as much as two days off from the real Moon, and this year, with Easter on March 23, Passover is April 19-26. And finally, he got the date of Easter in 2060 wrong. It is April 18 that year. Maybe he meant 2160, when Easter once again is March 23. There is an earlier possible date, which requires an epact which cannot occur this century: March 22. Next time it's that early is 2285.

More lunacy occurs in Newsbeat, from BBC. According to this article, "Easter always comes on the Sunday after the first full moon after the first day of spring." In a general sense, that is true. But really the rule should read "Easter comes on the Sunday after the first Paschal full moon after March 21." The equinox does not always occur on March 21. This year it was on the 20th. And the Paschal full moon, the one determined by the mathematical model, is March 22 this year, but the real full moon occurred on March 21. Further, the article says, "Easter will not come this early again for approximately another 220 years." That means in the year 2228. True, Easter is March 23 that year. But it is also on March 23 in 2160.

Where is there some sense on the Internet about Easter? Maybe in USA Today. That article does have the correct rule for Easter, but not the algorithm for computing it. Further, it explains the difference between the Paschal full moon and the real astronomical one. The Easter rule fixes the equinox on March 21, when for the next few decades, it will be March 20, or earlier. Using the astronomical full moon, Easter should be on March 28 in 2038, since the full moon is the 21st, and the equinox is on the 20th. But the Paschal full moon is on April 18 instead, since the previous mathematical full moon is March 20; it is off by a day. So Easter that year is on April 25, the latest possible.

This article also says that the Moon is never full. No, I don't think that is correct. There is a time of full moon, when the Moon is opposite the Sun and the lit portion stops increasing and starts decreasing. This may be altered by lunar terrain, but there has to be a turning point.

So celebrate Easter, on this early date. Maybe the date of Easter will be changed; there was a movement to do so in 1963, perhaps to the second Sunday in April. But remember that it can be changed. God does not determine Easter for us, we do.


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