Why Do Jewish Holidays Change Dates Every Year?

Those who constantly have to Google “When is Hanukkah 2016?” or “When is Yom Kippur this year?” will understand the confusion that is the Hebrew Calendar.

Jewish holidays may change on our secular (or Gregorian) calendar each year, but in the Hebrew calendar they actually stay the same year after year. Rosh Hashanah, for example, is always on the first of Tishrei, the seventh Hebrew month.

There are 12 months in the Hebrew calendar, just like the Gregorian one. They are named Nissan, Iyar, Sivan, Tammuz, Menachem Av, Elul, Tishrei, Marcheshvan, Kislev, Tevet, Shevat and Adar, respectively.

Contrary to popular belief, the Hebrew calendar isn’t just a lunar one. Chabad.org referred to the calendar as “Luni-Solar” because it relies on movements of both the moon and the sun. This is because, though the calendar months follow the lunar calendar, the seasons have to align correctly. Those seasons are governed by the sun, not the moon, so the calendar has ties to both.

Because the Jewish people use the Hebrew calendar instead of our Gregorian one, it seems like their holidays are constantly changing dates even though on the Hebrew calendar they’re always the same.

For those of you who would like to stay up to date on Jewish celebrations and holidays, you’re in luck: Chabad.org has a calendar for you with the Gregorian dates of every upcoming holiday.