Calendars

Q: Why do the Jewish holidays come late, or early, never at the same time?

A: The Jewish year is reckoned by the lunar calendar, not the Gregorian calendar which is observed by the Western world.

The lunar year consists of 354 days as opposed to the Gregorian calendar, which is 365 days. For this reason the Jewish holidays will always fall on the same date in the Jewish, or lunar, cycle but rarely will they coincide with the same secular date.

Pope Gregory the XIII established the Gregorian calendar that we use today.  In 1850 Pope Gregory mandated that a universal calendar be calibrated using the solar year, beginning on January 1.  At that time, several corrections needed to be made before they began using the new calendar.  First, 10 days had to be taken out of the year in order to gauge the correct date.  Understandably, the Pope’s actions caused great deal of frustration and anger by those who felt their lives had been cheated by fortnight.  Much later, when the original American colonies decided to adopt the Gregorian calendar, Benjamin Franklin wrote in his inimitable style and wit, “And what an indulgence is here for those who love to lie down in peace on the second of this month and not perhaps wake till the morning of the 14^th.”

The astronomers of Pope Gregory also saw a glaring problem in the computation of the solar year. The earth needs 365 days to complete its orbit around the sun, five hours, 48 minutes and 46 seconds. In order to compensate for the extra 1/4 day, a leap year was added every four years to correct the imbalance.  

The Jewish calendar, on the other hand, is dependent upon the appearance of the moon, hence the use of the term lunar calendar.  However, in order to remain within the framework of the seasonal year a leap year was added seven times every 19 years. Our leap year, unlike the Gregorian leap year that adds one day, consists of a full month.  All told, the solar and lunar calendars rarely agree on the same date.