Why is Easter on a Different Day Every Year?
How come Easter gets the wiggle room?
As you might imagine the date for Easter and when it is celebrated has a lot to do with ancient religious celebrations. The early church fathers wanted to keep Easter in close correlation to the Jewish Passover. Because the Jewish calendar was based on solar and lunar cycles, the date was moveable.
In today's modern Christianity, the celebration of Easter is based on the Paschal Full Moon. That is the first full moon following the Vernal Equinox or the first day of spring. Ancient astronomers calculated these dates and eventually, the idea became a tradition that Easter would be celebrated on the first Sunday following the first full moon after the Vernal Equinox.
As you might imagine we have simplified the answer in this narrative. For a more detailed explanation of why the date for Easter changes you can click here.
In case you are wondering the first full moon following the first day of Spring happened behind the clouds last night. Therefore this Sunday we will celebrate Easter.