Beyond the Moon
The first national mitzvah to the Jewish People is the sanctification of the new moon: This renewal of the moon shall be for you a beginning of new moons. (Shemot 12:2) The new month is to be determined by the actual sighting of the recurring new light.
Some have wondered whether the ancient Jewish people simply lacked astronomical knowledge of the lunar cycle, and therefore depended on actual sightings. But the mitzvah is certainly based on astronomical knowledge: Rosh Chodesh could only have been one of two days: the thirtieth or the thirty-first after the last moon. If the moon was sighted on the thirtieth day, and reported by proper witnesses, the court would declare the thirtieth day to be Rosh Chodesh. If there was no sighting, the thirty-first would mark the beginning of the month. But a closer consideration of the laws of sanctification of the new moon reveals that its significance and purpose are far more exalted than a precise astronomical determination. Now, other halachic determination of time — such as sunrise and sundown, which determine times for prayer and the entry of Shabbat and other holidays — have no parallel procedure. These are determined by astronomical certainty. The new month is different — astronomical certainty is not only not required, it is also insufficient — the month must be consecrated by subjective perception.
The first clue is that the beit din procedure has the features of a civil hearing, and has the definite stamp of human social relationship. It must be performed during the day, only by a bench of three judges, and two witnesses are required.
Second, if the new moon was visible to the judges and to all of Israel, or witnesses were examined but the court did not have time to complete the proclamation of “It is consecrated!” before nightfall, the thirtieth day did not become Rosh Chodesh. Instead, the thirty-first day began the new month. Obviously, then, it is not the actual sighting of a heavenly phenomenon, but rather the sanctifying enactment of the representatives of the community that determined the new month.
Rosh Chodesh, and the festivals that follow it, are referred to as mo’ed — a designated meeting time or place. They are meant to be mutual, voluntary meetings between
This explains other laws of sanctification as well. In the interests of the community, the representatives of the community may decide to declare the thirty-first day as the beginning of the new month, even if the moon was sighted on the thirtieth day, for example so that Shabbat and Yom Kippur would not fall on consecutive days. Furthermore, even if through error, or by design, or through being lead astray by false witnesses, the court designated the beginning of the month erroneously, the new month is still consecrated, and the festivals are set accordingly. When the details of the law are examined, it becomes evident that the sighting of the new moon is merely an inducement for the community to designate the new month. Once the community has declared it to be mo’ed — a meeting time —
And, the verse comes to life: This renewal of the moon shall be for you a beginning of new moons. Our perception of the renewed moon should inspire us to undertake spiritual renewal — not an astronomical calendar, but our own months, our own meeting times with
- Sources: Commentary, Shemot 12:2