Hebrew Calendar Definitions
A 12-month year in the Hebrew Calendar. A deficient common year contains 353 days, a regular common year contains 354 days, and a perfect common year contains 355 days.
A measurement of time in the Hebrew Calendar equating to 1080 parts or 3600 seconds. The use of hours has the advantage of eliminating fractions. Hours are calculated from 6 PM; thus 6 hours equates to 12 Midnight, 12 hours equates to 6 AM, and 18 hours equates to 12 Noon.
A 13-month year in the Hebrew Calendar. A 30-day month called Adar I is added in years 3, 6, 8, 11, 14, 17, and 19 of each 19-year cycle. The result is a year with 383, 384 or 385 days. Also referred to as a leap year.
The calculation of the average conjunction of the moon with the earth and the sun; it is based on the mean or average length of the lunar month, which is 29.53059 days. The Molad is not the astronomical conjunction.
A measurement of time in the Hebrew Calendar equating to 3 1/3 seconds. There are 18 parts to a minute and 1080 parts to an hour.
A one or two-day adjustment to the calculation of the Molad of Tishri. These adjustments enable the process of calculating the Molad to consistently achieve the greatest degree of accuracy in relationship to the cycle of the moon.
Calendar Rules used to
determine dates for God's Feast Days
Postponements are part of the process of calculating and declaring the date of the Feast of Trumpets (Tishri 1, the first day of the Hebrew sacred year), which in turn is used to set the year's dates for observing God's annual Holy Days. After calculating the Molad of Tishri, the following postponement rules are used to declare Tishri 1.
When Tishri's Molad or advancement occurs on a Sunday, Wednesday, or Friday, the declaration of Tishri 1 is advanced one day to a Monday, Thursday or Saturday (Sabbath) respectively. This rule prevents the Day of Atonement (Yom Kippur) from falling on a Friday or Sunday. Since Atonement is a complete day of fasting coupled with the command that absolutely NO work is to be done on the day, this rule prevents a fast day followed by a day of feast and rejoicing before God (the Saturday Sabbath) and vice versa.
When Tishri's Molad happens at or after noon (18 hours 0 parts), the declaration of Tishri 1 is delayed to the following day.
When Tishri's Molad of a common year occurs on a Tuesday (on or after 9 hours and 204 parts) the declaration of Tishri 1 is moved to the next day (Wednesday). Then, because of the above listed Rule One, the day declared as Tishri 1 is moved to Thursday.
When Tishri's Molad of a common year comes right after an intercalary year occurs on a Monday, at or after 15 hours and 589 parts, the declaration of Tishri 1 is advanced to Tuesday. This rule applies roughly once every 186 years.