Why isn't Yom Kippur on the same day each year?
Yom Kippur is ten days after Rosh Hashanah, the Jewish New Year and takes place on the ninth Day of the Hebrew month of Tishri.
In the Jewish calendar the months are based on the moon and the years on the sun, which means that Jewish festivals move about the Western calendar from year to year.
Yom Kippur falls in September or October.
What is the shofar and why is it used?
The shofar is a ram's horn which is blown to signal the start of the Days of Awe, when Jewish people think about all they have done in the past year and ask forgiveness from God. The shofar is blown again to mark the end of this period on the day of Yom Kippur.