Happy Thanksgivukkah! and oh, Happy Birthday Carol!

“The secret to staying young is to live honestly, eat slowly, and lie about your age.”

Lucille Ball

“Happy 39th Birthday Carol!”

“Happy Hanukkah!”

Looks like latkes instead of sweet potatoes this year! Chanukah and Thanksgiving: A once in eternity overlap.

This year features an anomaly for American Jews – The first day of Chanukah/Hanukkah  starts at sunset on Wednesday November 27 the night before Thanksgiving, on November 28, 2013.

It turns out that it has never happened before . . . and it will never happen again.

Thanksgiving is set as the fourth Thursday in November, meaning the latest it can be is November 28. November 27  is also the earliest Chanuakah can be.

The Jewish calendar repeats on a 19 year cycle, and Thanksgiving repeats on a 7 year cycle. You would therefore expect them to coincide roughly every 19×7 = 133 years.

Looking back, this is approximately correct – the last time it would have happened is 1861. However, Thanksgiving was only formally established by President Lincoln in 1863. So, it has never happened before.

Why won’t it ever happen again?

The reason is because the Jewish calendar is very slowly getting out of sync with the solar calendar, at a rate of 4 days per 1000 years (not bad for a many centuries old calendar!) This means that while presently Chanukah can be as early as November 28, over the years the calendar will drift forward, such that the earliest Chanukah can be is November 29.

The next time Chanukah falls on November 27 is 2146 (which happens to be a Monday). Therefore, 2013 is the only time Chanukah will ever overlap with Thanksgiving.

Of course, if the Jewish calendar is never modified in any way, then it will slowly move forward through the Gregorian calendar, until it loops all the way back to where it is now.

So, Chanukah will again fall on Thursday, November 27 . . . in the year 79,811.