Why is October not the eighth month?
The Jewish religious new year begins at the month of Passover (usually near the Christian celebration of Easter). Therefore, March or April would be the first month of the ancient Jewish year making September the 7th month and October the 8th. However, the Jews periodically have a second passover, and add a 13th month to the year in order to maintain their calendar correction. It’s similar to when we add a day in February every leap year to maintain calendar correction with the revolution of the earth around the Sun. So, periodically the Jewish religious year will add a month, which moves Passover towards April.
