Next Thanksgivukkah In 80K Years? Wrong!

The convergence of Hanukkah and Thanksgiving is not quite as rare as some have claimed.

Some of our older readers have already celebrated Hanukkah on Thanksgiving, and our younger readers may do so again, despite widespread Internet hoaxes claiming this has never happened before, or that it will not do so for 79,811 years:

Thursday, Nov. 29, 1888           2nd Night
Thursday, Nov. 30, 1899           5th Night
Thursday, Nov. 28, 1918           1st Night
Thursday, Nov. 29, 1945*         1st Night
Thursday Nov. 29, 1956*           2nd Night
Thursday, Nov. 28, 2013           2nd Night
Thursday, Nov. 27, 2070           1st Night
Thursday, Nov. 28, 2165           1st Night

*National Thanksgivings weren't uniformly accepted by all states, these two convergences were in states, such as Texas, that did not.

Fact-checking is very important.

So what has made this fallacy viral, and how does it happen that there were also times in years gone-by with convergences as well?

Some of the problematic impact came from an article in the Boston Globe which reported a "calculation" that Thanksgivukkah "won't repeat for another 79,043 years." They also reported:

The magic struck last November, when Dana Gitell, a marketing specialist at NewBridge on the Charles, a Dedham retirement community, was driving to work.

She knew the holidays were going to overlap this year "because I had seen a list of holiday dates on the back of a Combined Jewish Philanthropies calendar," recalled Gitell, the wife of Seth Gitell, a former Menino press secretary now working for House Speaker Robert A. DeLeo.

She was mentally running through a list of clunky names for the phenomenon — Hanukkahgiving? — when the more melodious Thanksgivukkah came to her.

Gitell, her sister-in-law, and a friend — an artist with New Yorker covers in her portfolio — promptly designed Thanksgivukkah illustrations and contacted, a hip Judaica site. Together, they created products including cards and a $36 T-shirt that reads "Thanksgivukkah 2013: 8 Days of Light Liberty & Latkes."

An article in Haaretz noted that she did not have permission to use the image she chose and received a cease and desist order on October 5.

And, on November 24, Joel Hoffman published a widely publicized article that quite oddly didn't take the "erev" Thanksgivings into account, apparently accidentally only looking at western day morning through evening overlaps. Since the Jewish approach to holidays is to begin at sundown, which this time of year is quite early, 4:19 pm where I live, some of our grandchildren may well be alive to light their menorahs and dine on latke-stuffed turkeys, during the next evening convergence of Hanukkah and Thanksgiving in 2070.

Mathematicians disagree about recurrence dates on their websites, so it does take work to arrive at what seems to be a truly accurate answer. The most helpful site seems to be of the three Lansey brothers, whose blog with correct information was already online in 2012!

These three brothers did historical research on past dates of Thanksgiving, and posted the years listed in the table above when Thanksgiving and Hanukkah overlapped. The years 1945 and 1956 are marked with an asterisk because certain states had not yet adopted the Federal date set in 1941 for Thanksgiving and instead retained the later one set by President Franklin D. Roosevelt (and mocked as Franksgiving).

The creator of the Intel 8086 chip, Steven P. Morse, pointed the convergence out on his website back in in 2012, although he did not adjust for the historical differences in the dates of Thanksgiving in years gone-by. He further explains the solar/lunar calendar drift issues involved:

"Chanukah-before-Thanksgiving occurred in the past, and with decreasing frequency as time went on, is because there is a slow drift between the Hebrew Calendar and the secular (Gregorian) calendar. That drift amounts to one day every 217 years. So in about 80,000 years it will drift by one full year and we'll be back to where we started.  At that time we will once again be lighting Chanukah candles at our Thanksgiving dinner."

Jonathan Mizrahi nicely illustrated this drift in the Hebrew calendar:

Understanding the Jewish calendar would require a further article because it is not a strictly lunar calendar. And — this may come as a surprise to some — the Jewish calendar begins with Passover, the original Jewish New Year according to the Torah which requires Passover to occur in the Spring. Originally ensuring the proper alignment of dates and seasons was accomplished through observation-based adjustments:

"..., when the fruit had not grown properly, when the winter rains had not stopped, when the roads for Passover pilgrims had not dried up, and when the young pigeons had not become fledged. The council on intercalculation considered the astronomical facts together with the religious requirements of Passover and the natural conditions of the country." — Comprehensive Hebrew Calendar, p. 1-2.

But then, in the fourth century, according to Judaism 101,  

"..., Hillel II established a fixed calendar based on mathematical and astronomical calculations. This calendar, still in use, standardized the length of months and the addition of months over the course of a 19 year cycle, so that the lunar calendar realigns with the solar years. Adar I is added in the 3rd, 6th, 8th, 11th, 14th, 17th and 19th years of the cycle. The current cycle began in Jewish year 5758 (the year that began October 2, 1997). If you are musically inclined, you may find it helpful to remember this pattern of leap years by reference to the major scale: for each whole step there are two regular years and a leap year; for each half-step there is one regular year and a leap year. This is easier to understand when you examine the keyboard illustration below and see how it relates to the leap years above.

It's nice to note that some of the children alive today will be here for the next Thanksgiving-Hanukkah convergence. May they be blessed to thrive!