Easter is regarded as a movable feast, because it is always the first Sunday after the full moon that falls on or after March 21. The colour used for this season is white or gold, symbolizing purity and new life. The Easter season begins with the Great vigil of Easter on Easter Eve, followed by Easter Day (otherwise known as Resurrection Sunday). The season of Easter is celebrated for fifty days, called The Great Fifty Days, until the Feast of Pentecost. On the fortieth day of Easter, we celebrate Ascension Day, the day that the resurrected Christ ascended into heaven.
(Anne E. Kitch, An Activity Book for Anglican Kids, 2006)