Ecclesiastical full moon a transliteration of the Aramaic word meaning Passover. The date of Easter is determined as the first Sunday after the "paschal full moon" falling on or after March 21 (the ecclesiastical fixed date for the Spring Equinox; the actual Equinox can fall on March 19, 20 or 21). This "full moon" does not currently correspond directly to any astronomical event, but is instead the 14th day of a lunar month, determined from tables. It may differ from the date of the actual full moon by up to two days. The use of tables instead of actual observations of the full
Tishri-years the years from the Autumn season, around the Autumn Equinox (Gregorian September 22/23). The New Years Day of the Tishri-years is called "Rosh Hashanah" ("Head of the Year"); it begins the Fall Feasts of Israel. Tishri 1, however, is not determined directly by its relationship to the Autumn Equinox. It depends on the determination of Nisan 1, which is the day after the New Moon closest to the Spring Equinox (within fifteen days before or after). Tishri 1 is the first day of the seventh month. Although the month number is always counted from Nisan, in the Tishri-years, the year