By Hadas Kuznits

PHILADELPHIA (CBS) — This year, for the first time ever, Thanksgiving and Hanukkah will overlap.

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Rabbi Albert Gabbai of Congregation Mikveh Israel says it’s quite unusual for Hanukkah to overlap with Thanksgiving.

“This year, Thanksgiving falls on the latest Thursday of November and Hanukkah occurs on the earliest day it can ever occur. And the reason there is this is because of the discrepancy in the Jewish calendar,” Gabbai says.

He says the Jewish calendar is based on the moon with about 355 days, while the Julian calendar is based on the sun with about 365 days.

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Therefore, every three years or so, an extra month, called Adar the second, is added to the Jewish calendar to keep the holidays and seasons in sync.

“The Hebrew calendar is based on a 19-year cycle. Out of these 19 years, seven of them are leap years. So this year we are going to have the extra Adar in March. Therefore, we are still way behind. Therefore, Hanukkah falls in November.”

Rabbi Gabbai says even with the extra leap month added, at some point the Hebrew calendar could cycle through the Julian calendar, but according to Jewish law Passover must happen in the spring.

Therefore, eventually the Jewish calendar will have to be reset, making it unlikely that Thanksgiving and Hanukkah will ever overlap again.

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