1. When did the Hebrew Lunar Solar Calendar come into use? 2. Many of the months appear to be named after Babylonian gods. So was this calendar invented during the Babylonian exile? 3. Also, is the solar portion of the Calendar currently based on the Gregorian?? And if it is based on the Gregorian, if the rest of the world were to adopt a new solar calendar, would the entire Hebrew Lunar Solar Calendar need to be recalculated??? 4. Last question: I have read that the first commandment is to observe the calendar. Based on Exodus 12:2. If there was a new calendar when the Jews returned from Babylonian exile, why was there not a new calendar for when the Jews returned to Israel in the 20th century???
1. The Hebrew/Jewish/Israeli calendar began with the exodus from Egypt and the giving of the Torah 3,329 years ago. It’s based upon lunar months which are adapted to the solar year (7 of every 19 years we add an additional month of Adar to make up the 11 day difference between the 354 days in 12 lunar months, and 365 days in the solar year, to make sure that Passover comes out in the spring (Shmot 23, 15), so it can’t be called just a lunar calendar. 2. Throughout the Tanach, the months are called by their number in the year, e.g. “the first (month) for you in the months of the year” (ibid, 12, 2). We find that they also had Hebrew names, e.g. Eitanim (=the strong ones= Tishrei, Kings I, 8, 2); Bul (=crop or flood= Marcheshvan, Kings I, 6, 38); Ziv (=shine=Iyar, ibid, 37). The Ramban (Shmot 12, 2) explains that the Babylonian names came back with the Jews when they returned to the Land of Israel with Ezra in 516 BCE, and they were kept to commemorate and honor that second redemption, just as the aforementioned numbering of the months counts from the first month of the first redemption, from Egypt. 3. No, it doesn’t revolve around the Gregorian calendar, but as I mentioned, we make sure that Passover comes out in the spring, so the months are lunar, but the year can be called solar. 4. You are correct! When we will renew the Sanhedrin, they will decide to have some commemoration of today's third and final return to Israel, as well.