raphael@crystal.ARPA (03/12/84)
References: "A guide to the solar-lunar calendar", B. Elihu Rothblatt, 1978, and "The comprehensive Hebrew calendar", Arthur Spiers, Berman House, 1952. There are 19 years to a cycle. They have 12 months, except for years 3,6,8,11,14,17,19, which have 13 months. Amazingly, the months in 19 years add up almost exactly to 19 years. The month is treated as if it were exactly 29 days, 12 hours, 44 minutes, 1 khelek. (18 khelokim = 1 minute). This figure is correct to the nearest khelek. Starting with new moon, use the month length to figure the next new moon. This method is used to calculate the moment of the new moon of Tishri (the first month) of each year, based on an assumption of the time of the new moon of Tishri for year 1. There are 4 reasons you might postpone Rosh HaShono (new year's day) past when the new moon is: 1. The new moon is after noon. 2. Rosh HaShono would fall on a forbidden day of the week (Wed, Friday, Tuesday). (Forbidden to prevent Yom Kippur from Friday or Sunday, which would interfere with Shabbos, and to prevent Hoshana Rabo from Shabbos, which would interfere with Hoshana Rabo) 3. The coming year would be too long (356, I think). 4. The previous year would be too short (382, I think). Years come in 6 lengths: 353, 354, 355, 383, 384, 385. (Short/medium/long, normal/leap). Months alternate 30-29-30-29... days, except that short years make the third month 29, and long years make the second month 30. You might expect 24 types of calendar (6 year lengths, 4 days for Rosh HaShono), but actually only 14 types (kevios) exist. If you know the kevio, you know the day of the week for every festival and you know which parshios (Torah readings) are doubled. Seasons follow a different calendar (based on a different opinion: Shmuel Yarhini instead of Abbaye, I think). They assume a year is exactly 365.25 days long. The year has four seasons. We start saying Tal UMotor (prayer for rain) the 60th day of the season of Fall. I have Pascal calendar and candlelighting-time programs if people are interested. raphael@uwisc 602-263-7764 Refoyl Ari ben Osher Yoysef