Easter - Date - Relationship To Date of Passover

Relationship To Date of Passover

In determining the date of the Gregorian and Julian Easter a lunisolar cycle is followed. In determining the date of the Jewish Passover a lunisolar calendar is also used, and because Easter always falls on a Sunday it usually falls up to a week after the first day of Passover (Nisan 15 in the Hebrew calendar). However, the differences in the rules between the Hebrew and Gregorian cycles results in Passover falling about a month after Easter in three years of the 19-year cycle. These occur in years 3, 11, and 14 of the Gregorian 19-year cycle (corresponding respectively to years 19, 8, and 11 of the Jewish 19-year cycle).

The reason for the difference is the different scheduling of embolismic months in the two cycles.

In addition, without changes to either calendar, the frequency of monthly divergence between the two festivals will increase over time as a result of the differences in the implicit solar years: the implicit mean solar year of the Hebrew calendar is 365.2468 days while that of the Gregorian calendar is 365.2425 days. In years 2200–2299, for example, the start of Passover will be about a month later than Gregorian Easter in four years out of nineteen.

Since in the modern Hebrew calendar Nisan 15 can never fall on Monday, Wednesday, or Friday, the seder of Nisan 15 never falls on the night of Maundy Thursday. The second seder, observed in some Jewish communities on the second night of Passover can, however, occur on Thursday night.

Because the Julian calendar's implicit solar year has drifted further over the centuries than those of the Gregorian or Hebrew calendars, Julian Easter is a lunation later than Gregorian Easter in five years out of nineteen, namely years 3, 8, 11, 14, and 19 of the Christian cycle. This means that it is a lunation later than Jewish Passover in two years out of nineteen, years 8 and 19 of the Christian cycle. Furthermore, because the Julian calendar's lunar age is now about four to five days behind the mean lunations, Julian Easter always follows the start of Passover. This cumulative effect of the errors in the Julian calendar's solar year and lunar age has led to the often-repeated, but false, belief that the Julian cycle includes an explicit rule requiring Easter always to follow Jewish Passover. The supposed "after Passover" rule is called the Zonaras proviso, after Joannes Zonaras, the Byzantine canon lawyer who may have been the first to formulate it.