So Easter Sunday will be here this Sunday, March 31, which is considered to be early in the year. In some years, Easter doesn't happen until April. Have you ever wondered why it changes every year and isn't on a set Sunday each year? Well here is your answer.  

Easter falls on the first Sunday after the first full moon after the first day of Spring. Since Spring arrived on March 20th and the first full moon arrived Wednesday of this week that would make this Sunday as the first Sunday after those two events and therefore make this Sunday as Easter Sunday.

Historically it was back in the year 325 AD that Christian church leaders established the astronomical requirements that we still use today.  Based on those requirements, Easter could fall anytime from March 22nd through April 25th.

In early times, there was some question of this formula simply because of different calendars that were used but in 1582 the much improved Gregorian Calendar was established  which became the norm in Europe and most of the world.

So now you know why!