You may have heard the next Thanksgivukkah won't come for 79,000 years. That's not exactly right. In fact, this is just the one time for a very long while that the second night of Chanukkah will coincide with Thanksgiving. But the first night of Chanukkah will fall out on Thanksgiving in 2070, and then again in 2165. 2070 is soon enough that most Jews under 30 will be there to celebrate. That's a long time, but it's on a time scale similar to the Jubilee, which is every 50th year.
I'll explain below why the number 79,000 is wrong for ecological and sociological reasons. But we have to make two other huge assumptions to even imagine a Thanksgivukkah in 79,000 years. One is that Thanksgiving will exist 79,000 years from now. Given that the United States has only been around for 200-some odd years, and that the nation-state hasn't even been around for a thousand years, that's a pretty big stretch.
The other is that Torah, Chanukkah and the Jewish people will still exist as a culture in 79,000 years. I'd bet on the second assumption sooner than the first, since religions and cultures live a lot longer than nations: rabbinic Judaism is about two millennia old, and what is possibly the oldest living culture, the Australian aborigines, may be on the order of 60,000 years old. But according to the traditional rabbinic understanding of Judaism, the Messiah should come long before that.
So where did people get the number 79,000 from? People assume the Gregorian and Jewish calendars will unfold mechanically for the length of human civilization, without adjustments. In that case, Chanukkah will wander forward with the Jewish calendar about 6 minutes a year, and won't come back round into fall/winter for 79,000 years. But all we have to do to keep Chanukkah and the other holidays in sync with the seasons is to add one less leap month every 7,000 years or so.
We have to do it, because Pesach (Passover) needs to be in the spring, "when the crops are judged" (Rosh Hashanah 1:2). Chanukkah needs to span the darkest night, the new moon closest to winter solstice. And most of all, we need our calendar and societies to be in sync with Nature.
That shouldn't be too hard to organize. After all, we've only had a fixed calendar since the time of the astronomically-savvy Shmuel, since maybe the 3rd century. For most of our history, we arranged our calendar by watching the skies and the rhythm of the seasons. We never even set when the next month started, until witnesses came to the Beit Din (court) to say they saw the crescent moon. It was so important to get this right that people were allowed to violate Shabbat in order to get there to testify!
In any case, if we can't get back into harmony with those rhythms, you can bet in a few centuries there won't be a Thanksgiving, or a Chanukkah, or even a Torah to teach us about Pesach.
So let's focus on 2070 first. Not only will the two youngest generations be around for Thanksgivukkah 2, but we will probably have a pretty clear idea about something everyone is worried about now: how severe is climate change going to get? Will the next Thanksgivukkah take place in a world where billions of people living on the coasts are turned into refugees? Will there be enough food in 2070 for the 8 billion people who will be alive then, when the normal growing season, and the ecosystem, might be changing rapidly in many places?
These are just big questions now, but by Thanksgivukkah 2 we will have concrete answers. So here's one more question, for those of us who will not be around for Thankgivukkah 2: what wish would you have for the generations that will be here, that will inherit this world we are co-creating?
Here's a suggestion: take a moment during Thanksgiving, when family and friends are gathered, to share not just the material blessings of the feast, but blessings of a different sort, the kind of blessings for when we won't see each other for a long time, blessings we might give the people we love before leaving this world. Blessings like this:
"May the next Thanksgivukkah be a time of health and abundance for all of you who will receive the world from our hands. May we together find a way to make sure that there is health and wealth and beauty not just for our family, not just for the Jewish people and humanity, but for all living creatures who share this planet with us. May the One bless us with the power and wisdom to birth a society that shows love to the world around us, that lives with love towards all beings.
Maybe you can add the priestly blessing that parents say to children on Friday night, or the prayer for Creation on neohasid.org. But remember, we who will ultimately pass this world on to our children will only get to wish this blessing once.
If we do it right, maybe we'll have a slightly better chance of making it whole to Thanksgivukkah 2. Maybe even to that Thanksgivukkah far beyond the horizon, in 79,000 years.