How is Rosh Chodesh being determined- sighting, molad, or some other method?
Bernard Dickman, Brooklyn, NY, USA
It is determined using the 19 year luni-solar cycle of Hillel. You can find more information about this on our website, see our Insights to the Daf for Ta'anis, Daf 10 #2. http://www.dafyomi.co.il/taanis/insites/tn-dt-10.htm .
Best wishes,
M. Kornfeld
Hi, Thanks for your response. However, the Mishnah on 8b could not have been referring to Hillel's calendar. Furthermore, once the calendar was fixed, there could not have been any issue to discuss.
I see; it was not clear from your question that you were referring to the times of the Mishnah.
There are a number of calculations that did not relate to the actuall appearance of the moon, which were taken into account when determining the day of Rosh Chodesh, as the Gemara in Rosh Hashanah 19b-20a tells us. When necessary, we would "shut up" witnesses, not allowing them to testify so that we would not have to make the day Rosh Chodesh (because of the above-mentioned calculations). Rashi there (20a DH bi'She'ar Yarchei) points out that the calculation of our Mishnah (not making more than 8 thirty day months) is one of the calculations that Chazal took into account, ignoring the testimony of witnesses on occasion.
It might also interest you to see the novel opinion of Rabeinu Chananel, which we referred to in our Insights to Rosh Hashanah 23, that the month was always determined only by calculation and not by witnesses. See http://www.dafyomi.co.il/rhashanah/insites/rh-dt-23.htm .
Best wishes,
M. Kornfeld