Why do Jewish holidays change their date

Question

Let’s say rosh Hashanah. It varies it’s date every year, but if the Jewish calendar is a fixed amount of days, wouldn’t it be earlier and earlier or later and later every year?

In: 4

Answer 1

Changing dates is btw not exclusive to the Jewish calendar. The Muslim Ramadan changes its date every year, too, as well as certain Christian holidays, like Easter and Pentecost.