Mean and mode if possible ;j
An ordinary (non-leap) year has 353, 354, or 355 days. A leap year has 383, 384, or 385 days. The three lengths of the years are termed, “deficient,” “regular,” and “complete,” respectively. Check out http://webexhibits.org/calendars/calendar-jewish.html .
But for you, my goyim friend, only 350 days.
So the modal average is 354? What about the mean average is that round about the same as the mean average in the Gregorian calender?
Yes it is. I once calculated that it loses (or gains, I don’t recall which) about 2 hours in every 19 year cycle (each cycle has 7 leap years and 12 ordinary ones) which means around a half day every century. So either there is a further correction that I am unaware of or there is a drift of a day every couple centuries.
To the best of my knowledge, there is a drift. Holidays are now celebrated a few days later than they were a thousand years ago. At the moment there are no plans to correct it, but as time goes on there will be a need to do so.
The entire reason for the leap year to begin with is because Passover must occur during the spring. Since 12 lunar months is only 354 or so days, without a leap year, the holidays would drift through the calendar (as happens in the Islamic calendar). So, every 7 out of 19 years an extra month of 30 days is added. Since this correction is being made to ensure that Passover occurs during the spring, I’m sure that in a few thousand years (if the messiah hasn’t arrived by then) we’ll have to make another one-time correction.
Zev Steinhardt
I found ths site: http://www.herbertwarmstrong.com/calendar_jewish_calculations.htm
and worked out that the mean average is ~365.2468222 for each 19 year cycle.
Incidently are halakim still used outside of calculating the length of a year?
Outside of figuring out the next molad (new moon) I have never used chalakim.
Zev Steinhardt
MC, you have the mean length of a Jewish year correct. (The difference between this figure and the true solar year, 365.2422 days, is what accounts for the gradual shift - about a day every 216 years - that Hari and zev mentioned.)
There’s a far more detailed site about the Jewish calendar here. Under the heading “Hebrew Year Length Frequencies,” he gives the modal length of a Jewish year as 355 days; this occurs 28.8% of the time.
IIRC 365.2422 is not the length of the solar year but of the tropical year (which is what counts anyway).