Rosh Chodesh Revealed: 10 Fascinating Things You Might Not Know

1. Rosh Chodesh is the day that marks the beginning of the Jewish month. Rosh Chodesh is the first day of every month, and in months that are 30 (as opposed to 29) days long, the last day is also considered Rosh Chodesh of the following month.

2. The Torah details special sacrifices that were offered on Rosh Chodesh in the Temple.

3. According to the Talmud (Tractate Rosh Hashanah), during the period when the Hebrew calendar was determined based on the sighting of the new moon, Rosh Chodesh (the onset of the new lunar month) was established by the Sanhedrin, who would examine witnesses claiming to have seen the new moon. If the testimony was accepted, the members of the court would declare the sanctification of the month by proclaiming, “mekudash, mekudash” (sanctified, sanctified). The news was then transmitted to all Jewish communities by lighting signal fires on specific mountaintops. At a certain point, the Samaritans began lighting their own misleading fires to disrupt the process. In response, the rabbis instituted that the announcement of the new month would be delivered by appointed messengers instead.

4. Today, Rosh Chodesh is determined in advance according to the calendar established by Hillel. On the Shabbat preceding Rosh Chodesh, an announcement is made in the synagogue to inform the congregation. Some have the custom to fast on the day before Rosh Chodesh, which is called Yom Kippur Katan (the “Minor Day of Atonement”), except before Rosh Chodesh Tevet (during Chanukah) or Rosh Chodesh Tishrei (Rosh Hashanah), in which case only a half-day fast is observed.

5. The Tanach seems to indicate that Rosh Chodesh was considered a day of rest. This can be detected in averses that note that both Shabbat and Rosh Chodesh were special occasions, for example: "The gate of the inner court... shall be shut the six working days; but on the Shabbat it shall be opened, and on the day of the chodesh (new moon) it shall be opened" (Yechezkel 46). In addition, Rosh Chodesh is referenced in the story of David: "Yonatan said to him, 'Tomorrow is the chodesh... and you shall come to the place where you hid on the day of the deed,'" implying that Rosh Chodesh was not a workday. The custom that women do not work on Rosh Chodesh is based on these biblical references.

6. Though some sources indicate that Rosh Chodesh is a regular day, many other sources note that it is a special occasion. This disagreement has halachic implications regarding the laws of Rosh Chodesh, primarily the prohibition of work. The discussion revolves around the verse: "And in the day of your gladness, and in your appointed seasons, and in your roshei chadashim (new moons), you shall blow with the trumpets over your burnt-offerings, and over the sacrifices of your peace-offerings." On one hand, this verse seems to indicate that roshei chadashim should be marked with trumpet blasts like festivals, but on the other hand, one can infer that roshei chadashim are not one of the festivals, since the verse specifically mentions roshei chadashim after it uses the general term 'your appointed seasons.'

7. During the time of the Mishnah and Talmud, Rosh Chodesh was considered a festive day. One indication of this is that four people are called to the Torah on Rosh Chodesh, similar to the intermediate days of festivals (Chol HaMoed). Additionally, a special Musaf offering was brought in the Temple on Rosh Chodesh. A baraita in the Talmud explains the difference between days when three people are called to the Torah and those when four people are called, such as Rosh Chodesh and Chol HaMoed, and notes that on the latter, people were generally not busy with work, which allowed for a longer Torah reading. Effectively, work was not performed on Rosh Chodesh, not because the day held a stricter status than other festivals, but because it was treated similarly to Chol HaMoed, a semi-festive day that is not considered a full holiday. Although abstaining from work is no longer a widespread custom today, this tradition reflects the day’s original importance.

8. Rosh Chodesh is also regarded in Jewish tradition as a special day for women. As such, it is written in halacha (Jewish law) that it is a praiseworthy custom for women to refrain from certain forms of work on Rosh Chodesh. This partial abstention is mentioned in the Jerusalem Talmud, which references the custom among women not to work on this day. In Pirkei DeRabbi Eliezer, it is stated that this custom serves as a reward for the women who refused to contribute their gold jewelry to make the Golden Calf. On account of their refusal, they were granted the ability to be continually renewed, like the moon. 

9. On Rosh Chodesh, it is customary to add Hallel to the prayer service. Though Hallel is typically recited in gratitude for miracles that occurred in Jewish history, no specific miracle is associated with Rosh Chodesh. According to the Maharal, Rosh Chodesh celebrates a miracle that is yet to come. While most festivals commemorate past miracles, Rosh Chodesh points to future ones. The future miracle, explains the Maharal, is symbolized by the birth of the moon. On Rosh Chodesh, the moon is reborn and grows over the course of the month. The moon is likened to spiritual light in the world. As the month progresses, that spiritual light increases, and Hashem’s name becomes more exalted. This future illumination is the miracle represented by Rosh Chodesh.

10. Rosh Chodesh is characterized as a day of atonement, as reflected by the sin offering brought in the Temple, as well as a midrash cited in Tractate Shevuot (9b), where Hashem, as it were, asked to be atoned for diminishing the size of the moon.