I have the following questions. How was Rosh Hashana observed in the time of the Bais HaMikdash? This breaks down in the following specific questions:
1. If witnesses did not show up on the 30th was the 30th and the 1st of Tishrei observed as Rosh Hashana? If it was observed as RH did that mean that Melacha was forbidden on both days? What about the RH davening for both days? (Gemara seems to imply from the fact that the Leviim on the morning of the 30th sang the song for a regular day that the RH davening did not apply.) (I also have to qualify the term "RH davening" as many of our current Tefillos did not exist in the times of the Bais HaMikdash.)
2. If witnesses showed up during the day of the 30th how was it observed?
3. If witnesses showed up after Mincha how was RH observed?
4. Once the Bais Hamikdash was destroyed how was it observed?
Wishing you all the best and best wishes for a happy Channuka.
The Mishnah in Rosh Hashanah (30b) tells us that even Jews in Yerushalayim used to keep two days of Rosh Hashanah during the time when Beis Din would be Mekadesh the Chodesh. Being that no one knew on the night of the thirtieth of Elul whether this would in fact be declared the first of Tishrei, meaning Rosh Hashanah, people had to abstain from Melachah on that day. Originally, Beis Din accepted testimony the entire thirtieth day. However, this once led to the Levi'im making a mistake with the proper Shir for the Korbanos (see the Gemara ibid. regarding the exact mistake made). Beis Din therefore decided that they would accept testimony regarding the new moon until Minchah of the thirtieth. If testimony was accepted, Beis Din declared that the thirtieth was in fact Rosh Hashanah, and the next day, the second of Tishrei, would be Chol. However, after Minchah Beis Din would no longer accept testimony, and the next day would be deemed Rosh Hashanah. In any event, people would always refrain from Melachah on the thirtieth of Elul, in order that people should not come to do Melachah on years when it would in fact be the real Rosh Hashanah (see Rashi 30b, DH "Nohagim"). After the Churban (when there was still Kidush ha'Chodesh with witnesses), Rebbi Yochanan Ben Zakai declared that testimony should even be accepted after Minchah, as the original reason for changing this was due to the possibility of the Levi'im making a mistake in their Shir. Being that this mistake was sadly no longer applicable, Rebbi Yochanan changed back to accepting testimony the entire thirtieth. This actually has practical Halachic ramifications even today. [The fact that the first day would always be kept as a Yom Tov no matter what (even if no witnesses came) elevated the first day of Rosh Hashanah as being the same as the second day of Rosh Hashanah (see Rashi in Eiruvin 39a, DH "v'Rebbi Yosi"). This means that, according to some opinions, they have "one Kedushah."]
All the best,