The Jewish Calendar: Where You Hang Your Holidays
I’ve discovered that the single most searched-for topic about Judaism online is “Jewish holidays.” Of course, as a rabbi, I love teaching about the holidays – their meanings, their traditions, their special foods, and so on. But I suspect that the reason it’s so searched-for is not just because people want to know what the holidays are, why the holidays are, and how do we celebrate them.
The real reason so many people are searching for info about Jewish holidays?
Nobody knows when the heck they are!
And it’s not like we’re keeping them secret. You know me: I like to talk about them every chance I get!
The issue is that if you’re looking at a regular calendar, what you might call a secular calendar (even though it’s structure was decreed by a 16th century Catholic pope), the Jewish holidays appear to fall on a different days every year!
What, do the rabbis meet in a smoky backroom every year and say, “How are we going to keep people guessing (and Googling) this year?”
In fact, the Jewish holidays are on the same day every year…on the Jewish calendar, that is.
We have our own calendar?
Yes, we do. And the Jewish holidays fall on the same day on the Jewish calendar every year. (Mostly. I’ll tell you about some exceptions in a minute.)
The mismatch between dates on the the Jewish calendar and the Gregorian calendar (introduced by Pope Gregory XIII in 1582 CE) occurs because the Jewish calendar has some major structural differences to compared to the Gregorian calendar.
If you want to know what those differences are, so that you can have a better understanding of Jewish time and how our holidays work, read on.
Is the Jewish Calendar Lunar or Solar?
The first major difference is that the Jewish calendar is what’s called a lunisolar calendar. That means that the length of months is determined by the cycle of the moon (how full or not it is), but the length of the year is determined by the cycle of the sun The average length of the lunar cycle, from new moon to new moon, is 29.5 days. So all Hebrew months are either 29 or 30 days long, to stay in synch with the moon, on average.
You’ll notice that these months can be a day or two shorter than the months in the (more purely solar) Gregorian calendar. The Jewish calendar also has twelve months. So every Jewish calendar year of 12 months comes up a few days shorter than the solar cycle.
This may not seem like a big deal, or even noticeable from one year to the next, but over time, well…it accumulates.
This is why the Muslim holy time of Ramadan appears to “float” throughout the year, over the course of many years. It’s because the Muslim calendar is a more purely lunar calendar.
But in the Jewish calendar, many of our holidays are connected to the agricultural seasons, determined by the solar cycle. Passover is always in the spring. Shavuot is always early summer. Sukkot is always in the fall.
So how do we synch up the holidays in lunar months with solar seasons?
Enter: The Leap Month
The Jewish calendar follows a pattern called the metonic cycle. In every 19-year cycle, 12 years are regular years, and 7 years are leap years. Unlike leap years on the Gregorian calendar, where we add 1 day every 4 years, the Jewish calendar adds one month in each of the leap years. So a leap year has 13 months in it!
This means that a given year of the Jewish calendar can has as few as 353 days or as many as 385 days. But on average, over the 19 year cycle, this system matches up the solar and lunar cycles perfectly.
You might say: The Gregorian calendar is so much simpler. Why go to all this trouble, just to hang on to this antiquated tradition of keeping lunar months? What are we, werewolves?
(Maybe some of us?)
In fact, many Jews are not only asking this question; they’re taking action. Some families these days move their Passover seder, for example, to a night other than the actual holiday, because it’s easier to have it on a weekend than in the middle of the week!
Now, in the distant past, lunar months made all kinds of sense. Many Jewish holidays are on the 15th of a given month because that’s when the full moon is! In a time before electric light, if you want to have a big public festival, when is it the safest to party the latest? On the full moon!
But John, you might say, we have electric light. And my boss and my in-laws, who I have to schedule around, don’t care whether it’s the full moon or the new moon or the Reverend Moon or Moon Unit Zappa. Why hang on to something so obsolete and inconvenient?
1. Tradition. And not just in the “Fiddler on the Roof” / my grandma would roll over in her grave / guilt-trip kind of tradition. Keeping the Jewish calendar lets us say that as near as we can figure, we are celebrating the holidays with almost the exact same timing as people from Bible did, three or four thousand years ago. There’s something cool about being a link in a chain that stretches back unbroken over 4,000 years.
2. Connection to nature. People feel more meaning in their lives when they feel connected to something greater than themselves. What if you could say: I am one with the sun, I am one with the moon, I am one with the seasons, and I am one with an entire people – all at once – just as God intended it for me when we received the Torah. What could be more “greater than yourself” than that?
3. Stickin’ It to the Man. This doesn’t appeal to everyone, but there’s something I love about the transcendent, countercultural nature of practicing traditional Judaism (complete with our own “underground” calendar!) from within a culture which, like it or not, passively plans its entire existence around a papal decree from 1562. You want to have an enormous dinner for 6 hours on a Tuesday night, because of that one time God went all Biblical on Egypt? And declared you a free person forever more? You go right ahead, Hero.
So that’s why the Jewish calendar seems weird compared to what you might be used to, and why you might want to consider following it anyway. There are a few other minor details, like how most fast days are moved to the next day if they fall on Shabbat, and how a couple of months vary in length to make sure Yom Kippur never falls on a Friday or Sunday. But we can talk about that another time.
I’d love to know what questions you have about the Jewish calendar. Please leave your questions or suggestions for future articles in the comments below!
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