Av (July 17, 2015)
The Molad for Av is Thursday, July 16th at 3:39 pm and 7 chalakim.
Rosh Hodesh Av is Thursday evening, July 16th and Friday July 17th.
The Fast of Tisha B’Av is on Saturday night July 25th and Sunday July 26th. The 9th of Av itself, falls out on Shabbat July 25th, and therefore the fast is delayed to Saturday night and Sunday, rather than on fasting on Shabbat (Friday night and Saturday).
Rosh Hodesh, High Speed Wireless Communication and Cyber Fraud in the Days of the Sanhedrin
In the Talmud in Masechet Rosh HaShanah on page 22b, we learn that when the Sanhedrin declared it was Rosh Hodesh, high speed wireless communication was used to notify all of the people that Rosh Hodesh had begun. This was done by lighting a fire on certain designated mountaintops. Lookout people who were stationed on other mountaintops would see that this fire was lit, and would light their own fire. Successive fires were lit on more mountaintops until the Jewish people as far away as Babylonia were notified that it was Rosh Hodesh. This practice continued until the first case of Cyber Fraud was detected. The Samarians began lighting fires at the wrong time, and the Jewish people mistakenly thought that Rosh Hodesh was declared. Once these fake notifications were detected, the Sanhedrin took measures to improve security and implemented a more secure communication protocol. Instead of lighting fires, messengers were dispatched to spread the word that Rosh Hodesh was declared. This increase in security, lowered the communication speed severely, and led to the adoption of two days of Yom Tov in Jewish communities outside of Israel. The method of using messengers for announcing Rosh Hodesh continued until approximately the year 360 C.E. (4119 on the Jewish Calendar) when the perpetual Jewish Calendar that we use today was established by Hillel the Elder.
The Structure of the Current Jewish Calendar
The Jewish Calendar is a Luni-Solar calendar. The months are determined by the moon, while the days are determined by the sun, and the years are adjusted to the solar calendar, so that the holidays fall in the right season.
In order to adjust to the solar calendar, some years in the Jewish Calendar have 12 months, while others have 13 months. The years that have 13 months are considered leap years. In every 19 year cycle of the Jewish Calendar, there are 12 regular years, and 7 leap years. The leap years are in the 3rd, 6th, 8th, 11th, 14th, 17th and 19th years of the cycle.
A lunar month is approximately 29 ½ days, but a real month must have a whole number of days. As mentioned in the Sivan blog entry, months of the Jewish Calendar are either 29 or 30 days long.
A regular year can have 353, 354 or 355 days, and a leap year can have 383, 384 or 385 days.
Each month, except Heshvan and Kislev always have the same number of days. Heshvan and Kislev can have either 29 or 30 days. The months generally alternate between 29 and 30 days, as follows:
Nisan – 30, Iyar – 29, Sivan – 30, Tammuz – 29, Av – 30, Elul – 29, Tishrei – 30
Heshvan – 29 or 30, Kislev – 29 or 30, Tevet – 29, Shevat – 30, Adar I – 30, Adar / Adar II – 29
A year that has 354 or 384 days is called “Kesidrah” (regular). Heshvan has 29 days and Kislev has 30 days.A year that has 353 or 383 days is called “Chaserah” (missing). Heshvan and Kislev both have 29 days.A year that has 355 or 385 days is called “Shelemah” (full). Heshvan and Kislev both have 30 days.
For those of you who will be fasting on Tisha B’av, I wish you a meaningful and easy fast.