Search Library

How is the date chosen?
Contributed by David Querido

  • TOP HAGGADAHS FOR 2023

The Hebrew calendar is a lunisolar calendar, meaning that months are based on lunar months, but years are based on solar years. The calendar year features twelve lunar months of twenty-nine or thirty days, with a leap month added periodically to synchronize the twelve lunar cycles with the longer solar year.  These extra months are added seven times every nineteen years in the month before Passover.  

Passover is a spring festival celebrated on the 15th day of Nisan, typically begins on the night of a full moon after the northern vernal equinox. However, due to leap months falling after the vernal equinox, Passover sometimes starts on the second full moon after vernal equinox, as in 2016.

Before the 4th century, when the calendar was fixed mathematically, to ensure that Passover did not start before spring, the tradition in ancient Israel held that the first day of Nisan would not start until the barley was ripe.  If the barley was not ripe this indicated that spring was not yet imminent, a leap month (Adar II) would be added.

In Israel, Passover is the seven-day holiday of the Feast of Unleavened Bread, with the first and last days observed as legal holidays and as holy days involving abstention from work, special prayer services, and holiday meals. Before the calendar was set mathematically,  the length of a month was determined by the time that the new moon was observed or at the time that the last crescent of the moon disappeared.   This made observing holidays that occurred on the first day of the month difficult to plan, so Jews historically observed these festivals for two days.  Although Passover is celebrated on the full moon, which is easy to discern,  many Jews observe Passover for an extra day, so that their celebration will coincide with that in Israel.
haggadah Section: Introduction

Featured clips


More clips from David Querido