There is considerable superstition surrounding Easter , with some of the folklore rooted in ancient pagan beliefs when this period was known as Ostara. Throughout the centuries, religious convictions have also identified "lucky" and "unlucky" practices to be observed or avoided during the Easter period. The date of Easter (or Ostara) corresponds with the lunar cycle of what's known as the Paschal Full Moon - and this is why the date of this festival or religious celebration varies year to year.