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Holiday Stories

Rosh Chodesh

HOW IS
ROSH CHODESH
DETERMINED

 

 

 

How is the Rosh Chodesh, (beginning of the month), of each month determined?

Look at the calendar, you say?

Wrong!! When the Bnei Yisroel reach Eretz Yisroel, they are to appoint a Sanhedrin - a court of learned men. This body of leaders will decide each month which day Rosh Chodesh will be.

The Jewish calendar is based on the cycle of the moon. If you've ever observed the moon in the evening sky, this heavenly body starts out looking like a very thin half circle and ultimately grows to the full circle in the middle of the month. Then it shrinks again to a sliver. These changes are called "the phases of the moon." At the very end of the month the moon isn't even visible in the night sky!
When the sliver of a moon appears again, it is a sign that the new month has arrived. Even though these phases can easily be calculated by the members of the Sanhedrin, many of whom are astronomers in their spare time, Hashem wants all of the Bnei Yisroel to participate in the Mitzvah of Kiddush Ha-Chodesh. So at the beginning of the month it is a Mitzvah for Jews to look for that sliver in the sky and head over to Sanhedrin to bear witness to the sight of it. Of course, thousands of Jews could turn up as witnesses and the Sanhedrin will hear each and every one's testimony. When the Sanhedrin finishes listening to the testimony and determines that there are at least two independent, reliable eyewitnesses that the new moon occurred on a certain date, they declare Rosh Chodesh (first of the month) and fires were set on the hilltops to announce the new month to neighboring communities who, in turn, passed the message along.

Later on, torches were deemed not reliable, and messengers were sent out to proclaim the date.

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