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Calculating the Date of Easter
The God Plays Dice blog has an entertaining post on how the date of Easter is calculated. Wikipedia has all the messy details of course, but the blog makes a good introduction to the topic. "Easter is the date of the first Sunday after the first full moon on or after March 21... [T]he cycle of Easter dates repeat themselves every 5,700,000 years. The cycle of epacts (which encode the date of the full moon) in the Julian calendar repeat every nineteen years. There are two corrections made to the epact, each of which depend[s] only on the century; one repeats (modulo 30, which is what matters) every 120 centuries, the other every 375 centuries, so the [p]air of them repeat every 300,000 years. The days of the week are on a 400-year cycle, which doesn't matter because that's a factor of 300,000. So the Easter cycle has length the least common multiple of 19 and 300,000, which is 5,700,000 [years]."
In the UK the academic year is split according to the date of Easter. I recall hearing about an effort to move to a "metric" system which doesn't depend on Easter. This suddenly makes a lot of sense...
I've always thought that it is more fun to say the date of Easter is "the first Sunday after the first full moon after the Spring Equinox," rather than March 21st.
It sounds so much more Pagan my way.
Just because the date (and what it commemorates) is meaningless to you, is it really necessary to cast all those who do care about it as irrational?
There, now it's an official Science article.
What I'm listening to now on Pandora...
Historical significance, for one. The history of time-keeping and astronomy are intimately tied to the need to celebrate religious events; this goes back much before Christianity. It's really a very neat subject, and it's really fascinating how much math developed simply out of a need to know when and how to throw a party for the gods.
Methinks many families that profess no especial religion nonetheless buy their children bunny figures, chocolate, and disgusting gelatin chicks in the springtime. These sort of articles, besides showing Christians when their religious day falls, also explain when to expect such mechandise in your local stores.
"Easter is termed a moveable feast because it is not fixed in relation to the civil calendar. Easter falls at some point between late March and late April each year (early April to early May in Eastern Christianity), following the cycle of the moon. After several centuries of disagreement, all churches accepted the computation of the Alexandrian Church (now the Coptic Church) that Easter is the first Sunday after the first fourteenth day of the moon (the Paschal Full Moon) that is on or after the ecclesiastical vernal equinox. Easter is linked to the Jewish Passover not only for much of its symbolism but also for its position in the calendar. The Last Supper shared by Jesus and his disciples before his crucifixion is generally thought of as a Passover meal, based on the chronology in the Synoptic Gospels..."
http://en.wikipedia.org/wiki/EasterWikipedia
The date of birth of Jesus was also pulled out of the ass of some Pope. Christian Holidays were set on their particular dates to get medieval folks to stop their 'pagan' rituals and instead celebrate Christian rituals. Christmas:Winter solstice Easter:Beginning of Spring (Ostara now for you Wicans). I'm such a lapsed Catholic I can't remember the Holy days for other celestial events.
I prefer Flambe as apposed flamebait.
Because they run a grocery store and need to know when to stock the chocolate bunnies and egg dyeing kits
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Do you ever cast UFO believers as irrational?
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WHO ATE MY BREAKFAST PANTS?
Agreed, the history of time-keeping is a very interesting and important subject, however, an arcane method of determining the date for a specific holiday belongs in the category of 'curious minutiae' and is in and of it self just an obscure exercise, except for the devout adherents to it's attending myths.
In his defense, the picture tagged with the story is pi.
I find it quite amusing that the birth of Jesus is pretty much set in stone (at least if I believe that day to be Christmas), but the date of his death (or resurrection) isn't.
Yes, it's set in stone on the wrong date. Shepherds were living outside with their flocks when Jesus was born, yet they wouldn't be doing this in December. It's too cold in Israel. In addition, Jesus died on Nisan 14 (the first full moon after the vernal equinox)... not on a Friday year after year.
"Nature doesn't care how smart you are. You can still be wrong." - Richard Feynman
I seriously doubt that Mary went around saying that she became pregnant despite being a virgin, for two reasons. First, everyone would have read between the lines and assumed Jesus was the product of infidelity, then as now. Saying that Yahweh was the real father makes you look like you're not just loose, you're also batshit insane. The cover story would have been that Joseph was the father.
What's far more likely is that the virgin birth is a later addition to the story of Jesus. In comic book terminology, this is a retroactive alteration of the continuity, or "retcon". "Hm... how do we explain the origin of Jesus' amazing superpowers? How is he able to walk on water, cure leprosy, and feed multitudes using a single loaf of bread, if he's just some average Jew? It's just not plausible, our audience will never buy it. I KNOW! We have a special "Origins of Jesus" issue in the Bible, where we reveal that ACTUALLY, Jesus is the son of God! Now, the fact that he has these amazing superpowers makes sense!"
It's exactly like how Marvel went back and created a backstory to explain the origins of the super-powers of the X-men. In the case of Marvel, alien visitors altered the DNA of ancient humans which resulted in mutants like Wolverine. In the case of the Catholic Church, a super-powerful being impregnates Jesus' mom. It's a really ancient theme. If you recall many of Greek heroes, such as Hercules, had gods for parents, which explained why they were so powerful. Achilles was more like the Incredible Hulk, in that exposure to magic (the waters of the River Styx in the case of Achilles, gamma rays in the case of the Hulk) give them their powers. But Odysseus is like Batman- he doesn't have any superpowers, he's just clever.
Your grasp of astronomical chronology far exceeds mine, then. I'm not a Christian and have no interest in the holiday per se, but thought this article was a fascinating piece of science history, and certainly learned more science from the underlying astronomy and the computation thereof than I would have gotten from any ten Roland Piquepaille rehashings of press releases he doesn't understand.
What I'm listening to now on Pandora...
Ah! The March of progress.
Next year it will be April again though.
paintball
Hey, it's not like religious people are all irrational! In fact, except for fanatics, it's like they have two brains - one to deal with day by day matters, and one for the church things. Which is a good thing, actually. But when you think about... well, it's quite a freakish notion.
Circumcision is child abuse.
I don't care about the myths - the chocolate bunnies and eggs are good enough for me.
Save the earth! It is the *only* planet with chocolate!
Excuse me, but please get off my Pennisetum Clandestinum, eh!
Yes, it's set in stone on the wrong date.
Right. Because we have to celebrate everything in exact intervals of one earth-sun-revolution, and only whole-number interval offsets from the time of the original event.
There's no such thing as the 'right' and 'wrong' date. An event happens. Choosing to celebrate that event once a year (where "year" is the amount of time it takes the earth to go around the sun once) is arbitrary in the first place. It would be just as 'right' to celebrate it every 12 moon-earth revolutions, or 2 mercury-sun revolutions.
If you're already going to base your celebration intervals on the convenience of how often one ball of rock revolves around one ball of gas because you happen to live on said ball of rock, you might as well always celebrate something on the 259th day of the year, or the 4th time the 4th day of the week falls in the 11th month of the year, or the 1st 7th day of the week following the vernal equinox.
Getting bent out of shape because the commemoration/celebration of an event doesn't have the same calendar date as the original event - especially when the original event occured in a time period where the calendar you're using didn't even exist - seems pretty silly. Especially when you're celebrating the birth/death of the son of God.
paintball
sub GetEasterDate {
my($year)=@_;
# http://www.smart.net/~mmontes/nature1876.html
my $a=$year%19;
my $b=int($year/100);
my $c=$year%100;
my $d=int($b/4);
my $e=$b%4;
my $f=int(($b+8)/25);
my $g=int(($b-$f+1)/3);
my $h=(19*$a+$b-$d-$g+15)%30;
my $i=int($c/4);
my $k=$c%4;
my $l=(32+2*$e+2*$i-$h-$k)%7;
my $m=int(($a+11*$h+22*$l)/451);
my $month=int(($h+$l-7*$m+114)/31);
my $p=($h+$l-7*$m+114)%31;
my $day=$p+1;
return (0,0,0,$day,$month-1,$year-1900);
};
$x='S24;r)>63/* h@<5+oZ)32"5cz';$me='phroggy'x$];
$x=~y+ -xz+\0-Tx+;print$_^chop$me for split'',$x;
I won't hesitate to recommend the book 'Marking Time' by Duncan Steel - it's a great book about the history and evolution of calendars. The date of easter is a particularly interesting question and Duncan goes as far as to explain how the date of Easter was at the core of an English plan to attack the legitimacy of the Catholic church and how this plan was what triggered Britain's first attempts to colonize America, great stuff.
Methinks many families that profess no especial religion nonetheless buy their children bunny figures, chocolate, and disgusting gelatin chicks in the springtime. These sort of articles, besides showing Christians when their religious day falls, also explain when to expect such mechandise in your local stores.
Don't forget about Mardi Gras!Mardi Gras (Fat Tuesday, Shrove Tuesday, Pancake Day, etc.) is the day before Ash Wednesday, which is the first day of Lent, which begins 40 days (excluding Sundays) before Easter. So, once you've calculated the date of Easter, subtract 47 to get the date of Mardi Gras.
$x='S24;r)>63/* h@<5+oZ)32"5cz';$me='phroggy'x$];
$x=~y+ -xz+\0-Tx+;print$_^chop$me for split'',$x;
Calendars are funny things.
Those who fail to understand communication protocols, are doomed to repeat them over port 80.
the way he would have had to if this were a Muslim story
Or, you know, a Jewish or Christian one. The penalty of death by stoning for adultery is straight out of the Old Testament.
The correlation between ignorance of statistics and using "correlation is not causation" as an argument is close to 1.
Even worse... there are Christian women on /.
Seriously, do you assume that all Christians are no-brain idiots who think dinosaur skeletons are an atheist conspiracy? Donald Knuth is a Lutheran, Gregor Mendel was an Augustinian monk, Copernicus was a priest, as was Georges Lemaitre. Lord Kelvin and Max Planck were committed Christians, Arthur Stanley Eddington was a Quaker... There are more here: http://en.wikipedia.org/wiki/List_of_Christian_thinkers_in_science (Not all of those in this list were Christians throughout their lives, but the ones I've named were/are.)
A closed mouth gathers no foot.
There are millions of people who did not celebrate Easter today (23 March 2008) because they will be celebrating on 27 April 2008 (yep, 5 weeks later ... this is an unusual year). Orthodox Easter is computed to always fall after Passover (because, recall, the Last Supper was a Passover Seder).
Here's a web site that is more, um, shall we say, enlightened: http://www.assa.org.au/edm.html
One of the main differences between the calculations for Roman Catholic Easter and Eastern Orthodox Easter is in which calendar (Gregorian or Julian) is used. Use Google. It's actually quite interesting because of all the history and politics involved. It's not just simple (eg, exactly when is the moon full? over which point on the earth?) as one might think.
Put my fist through my alarm clock with its ding-dong death inside my ear. - The Blackjacks.
If you want to say that Passover's date is set at spring pagan holiday time, you'll need to argue with your rabbi or maybe Lehrhaus Judaica about whether your druids are at all the same kinds of pagans as Caananites were. And if you want to say that the name "Easter" and the bunnies and and eggs and marshmallow chickens are ripped off from Germanic spring fertility goddess stuff, you'll have a tough time getting anybody to argue the other side except maybe some atheists who'll say that the Germanic fertility goddess folks ripped that off from nature, which provided the bunnies and eggs, or from the chemical industry who brought us marshmallow peeps.
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
The date IS fixed -- it's all a matter of perspective. Dates are divisions of a calendar, and a calendar tracks time using periodic and regular astronomical events. Obviously, the easiest of these is the day, since it's easy to tell when the sun rises, and our body clocks (and therefore the work day) are tuned to it. Unfortunately, days are too granular: to really organize a civilization, you need larger logical units (such as weeks, months and years). Nowadays, we use a calendar which tracks the sidereal year -- the time it takes for the earth to complete one full orbit. For agricultural purposes, this is ideal, since it will tell you when to grow your crops. Unfortunately, it was a tricky one to calculate: even if you know that the earth orbits the sun, you're stuck dealing with the fact that the orbit is nearly circular so you can't find a visible difference in size in the sun, and the stars are so incredibly distant that there's no appreciable parallax. One cue that you CAN watch for is the equinox, and this is exactly what early calendars did to track the seasons. Your typical farmer isn't going to have the time or the tools to measure when the day and night are of equal length, but he can get a general feel for it, and you can have a few people set aside whose job in the springtime is to watch the length of each day.
For the common man, an easier thing to watch is the moon. The phases of the moon are not only regular, but they're highly visible and uncomplicated. This means that if your calendar has something to do with the moon, then it's not only easy for your astronomers to track, but it's easy to explain to the unwashed masses: just tell them the festival is on the next new or full moon, and they'll know exactly what you mean. You can also track days for a very small number of days; 7, for instance. You can tell people "go out and work really hard for 6 days, and on the seventh, take a break," and most people can do that (and those that can't can just notice that those who can aren't working on some days). In the Jewish tradition, as you're probably aware, the seventh day is called the Sabbath, and is considered sacred.
A mix of the two was popular -- the accessibility of the lunar calendar was nice, but the agricultural significance of a sidereal calendar was needed as well. For the Liturgical year, the calendar starts with the first new moon after the spring equinox. This means that there's not even any pretense that the calendar is equivalent to a sidereal year; the orbital period of the moon just isn't any fraction of the orbital period of the earth.
Easter tries to mix the 3 logical units of measurement: the rules are complicated, but it essentially boils down to finding a date which 1) falls on a Sabbath, 2) comes quickly after an equinox and 3) ties into lunar phase. The way they chose was to set it at the first Sabbath following the first full moon following the spring equinox. But, approximations are applied to make it easier to plan: ancient astronomy was amazing for what they had at their disposal, but really very far from perfect. So, since the need to plan out a major annual festival was superior to the need for people to be able to look in the sky and see it get close, approximations were accepted over time. The "full moon" was assumed to occur 14 days after the new moon, which was in turn predicted from tables generated using an agreed-upon system of reckoning. The equinox was eventually taken to occur on March 21. The end result is that it no longer actually directly corresponds to an equinox or a lunar phase, and is instead based off of approximations that were chosen to make the date easier to work with. Nowadays, the approximation that most proponents of Easter date reform put forth is just to pick something like the first Sunday of April and use that. Others want to go back to a pure lunisolar basis and throw out the approximations. At this point, however, there's not much motivation to do either: we can compute Easter out arbitrarily far now, and it's printed on every c
Yes and no. In the Hebrew Bible, the word used by Isaiah is rightly translated as "young woman." In the Septuagint (the Greek translation of the Hebrew Bible produced nearly 200 years before Christ, and much older than the oldest extant Hebrew language Bible), however, the word is in fact "virgin."
Many Christians themselves, not to mention those who don't know much about the religion (no offense, but the majority of /.), are unaware of the fact that the Apostles themselves would most likely have used the Greek scriptures--indeed, it is apparent throughout the New Testament that the Hebrew scriptures being quoted nearly all are of Septuagintal origin.
To reign is to serve.
One still has to take into account what is really going on when the word 'virgin' is used, based on the context of the writing. Even if the translation is literal, a writer might assume that a young woman is 'virginal' when she is, in fact, not. At any given time, not many people have that actual knowledge about an individual, and so it is usually nothing but an assumption, in any time or place. And given the actual record of history, that assumption is probably wrong more often than right.
> ...same-sex activity is normal for many mammals,
> contrary to the ignorant ramblings preached from pulpits every weekend.
You fail Critical Thinking 101.
You can't get an "ought" from an "is". See http://en.wikipedia.org/wiki/Is-ought_problem
The fact that certain behaviors among animals can be observed in nature doesn't imply any moral (or amoral) imperative among humans. There are lots of things animals do that no one would consider OK for humans to do.
If you disagree with me on social issues, then it's pretty clear that you are a narrow-minded bigot.
The date of Christ's death is fixed on the Jewish calendar. There are other comments giving possible actual dates listed here. I personally subscribe to the 15 Nisan 31 CE date (putting the crucifixion on a Wednesday), but I don't have problems with people who prefer 14 Nisan on a different year. Passover always starts with a day of preparation on 14 Nisan, each and every year, followed by the seven day passover feast. If you go through the chronology of the Bible, you'll then come up with a crucifixion on either the day of preparation or Passover itself. This is followed by three days in the grave and a Resurrection on the Jewish first day of the week (any time Saturday sunset to Sunday morning when the tomb was seen to be empty).
The whole problem is that the Jewish calendar doesn't match up with ours. Its months are based on the lunar cycles and tend to have fixed lengths. In order to keep in sync with the Earth's rotation around the sun, leap days are added as needed and every few years a leap month is added. These are always added at the end of the year. Thus, 15 (or 14) Nisan is always a fixed date on the Jewish calendar since it's in the first month of the year, but it won't match to a fixed date on the Gregorian calendar. Likewise, the day of the Resurrection (three days after His crucifixion) will not always come on a Sunday since Passover moves w.r.t. the Gregorian calendar, which irritated a Bishop back in the early hundreds, and caused the goofy Easter mess in the first place. If you want a modern day parallel, look up Golda Meir's date of death. If you were to commemorate this as a Jew, you'd almost certainly do it on the same date on the Jewish calendar each year. Yet this moves the date on the Gregorian calendar around the same way Passover moves. Last year, it (8 Kislev) would have been November 18 Gregorian. Next year it will be December 5. The year after, it'll be back in November.
If you're really interested, you should study what the passover was about (instituted long, long before Christ was born), and look at how perfectly it was a type of Christ's death. It's really fantastic. Even the actual Jewish passover rituals are a type of Christ's death, burial, and resurrection. It's a shame not many Jews have really seen that yet. The next passover, when He returns for His church in the air will be just as great an event. We don't know when that will be, but many of the Christian "big events" (Christ's birth, Christ's death, the initial outpouring of the Holy Spirit) have occurred at the times of established Jewish festivals.
I tend to agree that we should celebrate Christ all the time and not just on one day, but I'd like to see it move to be in sync with passover, regardless of whether that happened to put it on a Sunday or not on the Gregorian calendar. They ought to get Maundy Thursday and Good Friday corrected while they're at it.
And yes, the December 25th birth date is just as goofy - both for reasons of a fixed Jewish calendar date never being fixed on the Gregorian calendar, and for it needing to be tied to the Feast of Tabernacles which is much earlier in the year (15 Tishri). A good bet for a birth date would be October 4, BC 4 (Tishri 15, 3757) according to some sources.
Getting bogged down in debates over dates obscures the most important facts. He was crucified to provide a holy sacrifice for our sin. He bore stripes for our healing. Roman guards were posted to guard the tomb under penalty of death if anything happened to the body. They didn't count on angels showing up and rolling away the covering rock (not that Christ needed angels help - that was for the benefit of the people who would come). He arose, just as He said He would after three days. He arose with keys to the death and the grave, and led those righteous souls who were being kept under Satan's control in the grave to heaven. He appeared bodily to hundreds after that point in time (and at the time of His resurrection, many others who had died were also seen in Jerusalem before going to Heaven). He is reigning on the right hand of God. At some point, God will send Him to gather up His church. You don't want to miss that time.