Bais HaVaad on the Parsha

Parshas Hachodesh

Man and the Moon

Adapted from a shiur
by Dayan Yosef Greenwald

This month is for you the head of the months…. (Shemos
12:1)

The mishnayos in Rosh Hashanah describe the
performance of this mitzvah during the period of Bayis Sheini and beyond:
Witnesses came to the Sanhedrinand testified that they saw the new moon.
The Sanhedrinwould interrogate them and then declare “mekudash
mekudash,” making that day Rosh Chodesh. Bonfires would be lit on a
series of mountaintops to communicate the date of Rosh Chodesh to all the
communities in Eretz Yisrael and Bavel. When this method was undermined by
sabotage, they sent messengers to the communities. In the time of the Amora’im,
astronomical calculations were used. When this practice, too, was subverted, Hillel
Hanasi (a contemporary of Abaye and Rava) implemented the fixed calendar that we
have used ever since.

Who is qualified to perform kiddush hachodesh?
According to the Rambam (Hilchos Kidddush Hachodesh 5:1; Sefer
Hamitzvos, Asei 153), it is the province of the Sanhedrin, but they can authorize
another bais dinin Eretz Yisrael to perform it. It seems that the
Rambam holds kiddush hachodesh is not a p’sak din; rather, Klal
Yisrael, represented by the Sanhedrin,chooses when the month will begin.
This can be done by any bais dinin Eretz Yisrael when needed, and
when there is none, Klal Yisrael themselves can do it.

The Ramban (Hasagos on Sefer Hamitzvos)argues
that declaring “mekudash mekudash” is a p’sak din that may be
issued by any baisdinof semuchin. Hillel Hanasi was mekadesh,
inadvance, every future Rosh Chodesh.