For Christians, the Easter season ends this coming Sunday. The season, with its focus of commemorating Jesus' resurrection and its meaning for the world, always lasts fifty days, beginning with Easter Sunday.
Easter Sunday is one of the three great festivals of the Church Year, along with Christmas and Pentecost. Christmas, when Christians celebrate Jesus' birth, is referred to as a fixed festival, the designated date always being fixed at December 25.
Easter is what's known as a movable festival. Because Pentecost always comes seven Sundays after Easter Sunday, its date moves as well.
So, how is the date of Easter determined? The death and resurrection of Jesus, of course, happened during the Jewish Passover. (Jesus was a Jew, as were all His first followers.) The date of Passover is determined by the phases of the Moon. Although there are several different Christian traditions for determining when the actual festival of Christ's resurrection is to happen, most Christians use Passover to determine the date of Easter on their calendar. For most, Easter then, is celebrated on the first Sunday after the full moon that comes following March 21. The earliest date on which Easter can fall is March 22 and latest date is April 25.
This coming Sunday, May 23, will bring Christians to this year's celebration of Pentecost, the day that kicks off the longest-running season of the Church Year. But more on Pentecost later.