I´m, the LORD, your God.
The Jewish calendar is a lunisolar calendar, that is, it that is based not on the Earth cycle around the Sun (a year), but also on the Moon cycle around the Earth (a month).
Our calendar has 12 months (13 on leap years); half of these months have thirty days and the other half twenty-nine.
Rosh Chodesh –(lit. means "Head of the Month") is the name for the first day of every month in the Hebrew calendar, marked by the appearance of the new moon.
At the end of 30-day months, Rosh Chodesh is observed during two days, on the 30 of the previous month and on the first day of the new month. On 29-days months, only is observed as Rosh Chodesh the first day of the new month.
The connexion between Rosh Chodesh and women goes back to the Torah. According to the Midrash Pirkei of Rabí Eliezer, the women refused to take part on the construction of the golden bull and they were rewarded with Rosh Chodesh.
The Talmud of Jerusalem quotes the women’s custom of not working at Rosh Chodesh as a legitimate custom, an issue that is also mentioned in almost every code, including the Shulchan Aruch (Oraj Jaim 417).
Other Jewish sources give different reasons on why Rosh Chodesh is a women’s festival. Rabbi Itzjak ben R. Moshe of Vienna quotes the similarity between the moon cycle and the women’s menstrual cycle.
Rabbi Itzjak tells that, just like the moon renews itself every month, women also renew themselves every month (or Zaruah, Nidah’s Laws, 360).
In the book “Celebrating the New Moon: A Rosh Chodesh Anthology”, an article and texts anthology on Rosh Chodesh, compiled by Susan Berrin, we learn about the connection between the moon and women’s menstrual cycles, and also how the moon phases teach us the importance to prepare ourselves to the changes that we experience every month and to take a period of rest. We need to take care of our body, to know it well, to love it so we can renew ourselves, like the moon does month after month.
The authors also tell us how the moon phases, their connexion with the women’s body and the changes associated with it show us that we can overcome women’s models prevailing in our society to find the physical and spiritual beauty in all the stages of our life.
Nowadays, Jewish women see Rosh Chodesh as a symbol of renewal, a pact, a reminder of nature cycles, and as a mark in time. Rosh Chodesh is a monthly opportunity to grow spiritually, to take care of ourselves, to learn and to share. (Jewish Women’s Center of Pittsburgh)