Can any other MOTs remember any other year when Hanukah started so late? I seem to remember one year when it started Dec. 26, but when was that?
In any event, Hanukah now goes beyond Christmas, all the way into 2006 (Gregorian). Yay! ;j
This suggests that it was almost as late in 1997.
Last year was a Hebrew leap year, the extra month necessary to ensure that Passover took place in the spring. Since Passover would have just barely missed spring without the leap month, the leap month made all Jewish holidays for 2005 very, very late. I believe this year does mark the latest that they come out.
So late? - isn’t it always the 25th of Kislev? 
Seriously though, Hanukah started on the 27th in 1986, the 25th in 1978, 27th in 1967. You can go through some dates to see when Hanukah will be here.
How often is it on the same day as Christmas?
1967 + 19 = 1986, so the fact that it started on the same Gregorian date both years is not exactly surprising! That’s because the Jewish calendar has a 19-year cycle with 7 leap-months, that together add up to 19 Gregorian years.
I don’t think that’s quite right. The Jewish calendar is on a 19 year cycle, but that doesn’t mean every 19 years Hanukah will begin on the 27th. Converting between the Jewish and Gregorian calendar is a little more complicated than that.
Here are a couple references concerning the Jewish calendar:
Jewish Calendar
Judaism 101 - The Jewish Calendar: A Closer Look
Wikipedia
Hebrew Calendar Conversion Sample Code in VB.Net
Generally speaking, the Gregorian and Jewish calendars will sync up again every 19 years.
However, the system is not perfect. 19 Jewish years are actually about 2 hours longer than 19 Gregorian Years. As a result, there is a shift of one day every 216 years.
Therefore, as time goes on Channukah will come out later than it does now (although maybe not in my lifetime). Eventually, some correction will be needed - or else the messiah will come and the problem will be fixed then.
Zev Steinhardt
I am confused by this. Could you please explain? Does this suggest that one of the two has days that longer/shorter than the other?
While its true the number of days will sync up, the actual dates do not. With 7 leaps years and Cheshvan and Kislev both varying in the number of days per month, the actual dates are close, but not always the same.
Take the last 4 19 year cycles. The current cycle of 19 began in 1997, with the preceding cycles starting in 1978, 1959 and 1940, respectively.
In order: 1940, 1959, 1978, 1997
Year 1 (starting with 1940): Dec 25, Dec 26, Dec 25, Dec 24
Year 2 (starting with 1941): Dec 15, Dec 14, Dec 15, Dec 14
Year 3 (starting with 1942): Dec 4, Dec 3, Dec 3, Dec 4
Year 4 (starting with 1943): Dec 22, Dec 22, Dec 21, Dec 22
Year 5 (starting with 1944): Dec 11, Dec 11, Dec 11, Dec 10
Year 6 (starting with 1945): Nov 30, Nov 30, Dec 1, Nov 30
Year 7 (starting with 1946): Dec 18, Dec 19, Dec 19, Dec 20
Year 8 (starting with 1947): Dec 8, Dec 8, Dec 8, Dec 8
Year 9 (starting with 1948): Dec 27, Dec 27, Dec 27, Dec 26
Year 10 (starting with 1949): Dec 16, Dec 16, Dec 16, Dec 16
Year 11 (starting with 1950): Dec 4, Dec 5, Dec 4, Dec 5
Year 12 (starting with 1951): Dec 24, Dec 23, Dec 23, Dec 22
Year 13 (starting with 1952): Dec 4, Dec 3, Dec 3, Dec 4
Year 14 (starting with 1953): Dec 2, Dec 1, Dec 2, Dec 2
Year 15 (starting with 1954): Dec 20, Dec 20, Dec 20, Dec 21
Year 16 (starting with 1955): Dec 10, Dec 9, Dec 9, Dec 9
Year 17 (starting with 1956): Nov 29, Nov 29, Nov 28, Nov 28
Year 18 (starting with 1957): Dec 18, Dec 17, Dec 18, Dec 17
Year 19 (starting with 1958): Dec 7, Dec 5, Dec 6, Dec 7
So maybe I’m going a bit overboard here, but the Jewish calendar doesn’t work out easy enough to say that Hanukah begins on Dec 25th every 19 years - saying so oversimplifies the Jewish calendar and the engineer in me cries foul! 
Quick attempt:
The length of time it takes for the earth to complete its orbit around the sun is approximately 365.26 days to orbit the sun. The earth takes approximately 24 hours to rotate on its axis.
In order for the Gregorian calendar and Jewish calendars to not “lose time” using days they both incorporate “leap years” where either (or both) a day or month is added to the year so that there is no change in the seasons (long term).
In any given year, the Gregorian nor the Jewish calendar align with the solar year, because you can not have partial days. It’s over time that both calendars attempt to align with the solar year. It’s in this attempt that the Jewish calendar would be off from the Gregorian, because they do not use the same number of days - they just try to average to the same number of days over a period of time. It’s their long term average that is off by hours.
Thanks, gooftroopag for the explanation. I learned something new today.
Hear tell he already came and why we celebrate 2005 A.D.
I know I was oversimplifying. But I wanted to work the 19-year cycle into this thread and I was pressed for time. I knew I could count on at least 5 Dopes to come along and pick all the nits I had left lying around 
cmkeller: Some time ago I ran across a web site from what I basically must call an extremely fundamentalist Jewish sect. Sadly, I can’t recall the name of the sect. The site was mainly concerned with the calendar and was pretty adamant about not having any leap months. Have you heard of such an outfit?
Dopers, even :smack: Freud would have been proud of me 
Monty:
Nope. I’ve never heard of anyone objecting to leap months in the Jewish calendar cycle.
Muslims use a lunar calendar with no leap months, and as a result their months roll around the solar year. Maybe it was a Muslim site.
MOTs?
Mothers of Time? Medicinally Organized Truckers?
I give - what’s an MOT?
Nope. Definitely a Jewish site. FWIW, I also recall they had a big problem with much of Rabbinic Judaism.
Karaites, maybe?