WORD OF THE MONTH

A weekly feature of Torah Tidbits to help clarify practical and conceptual aspects of the Jewish Calendar, thereby better fulfilling the mitzva of HaChodesh HaZeh Lachem... 

We bench Rosh Chodesh Nissan this Shabbat

ROSH CHODESH NISSAN Y'H'YEH MACHAR B'YOM RISHON HABA ALEINU V'AL KOL YISRAEL L'TOVA

Rosh Chodesh Nissan will be tomorrow, Yom Rishon (Sunday)...
The Molad will be Shabbat afternoon, 17h 41m 10p
First opportunity Kiddush L'vana (Minhag Yerushalayim, i.e. 3 days from the Molad) is Tuesday night, March 27th

Although the main fulfillment of the mitzva to set up a Jewish Calendar falls upon the shoulders of the Sanhedrin, there is an aspect of the mitzva that is of a personal nature for each and every Jew. And that is, to know your calendar. It is sad how many Jews can complete the ditty, 30 days hath September, but are ignorant of which Jewish months have 30 days. Tishrei, Shvat, Adar Rishon, Nissan, Sivan, and Av always have 30 days in our fixed calendar. Tevet, Adar (and Adar Sheni), Iyar, Tammuz, and Elul always have 29 days. Cheshvan usually has 29, but in "full" years, it has 30 days. Kislev usually has 30 days, but in "short" years, it has only 29. What determines a "short", "full", or "in order" year is the day of the week of Rosh HaShana at either end of the year. In other words, first a year's R.H. is fixed according to various rules, then the following R.H. is also established, and then Cheshvan & Kislev "fall into place".