The celebration of Easter changes with the cosmos. 
Easter is a so-called "moveable" feast. Unlike Christmas, Easter is celebrated at different times each year. We celebrate it on the first Sunday after the first full moon of the spring equinox.
In the Northern Hemisphere, Easter signals the time of rebirth, the strengthening of the sun, the fresh beginnings of the new life of spring.
It's no wonder that the Church decided to fix Easter to the timing of spring. Easter is a celebration of life. Earth flows with the sap of life, budding leaves and flowers, sugared sap cruising the innards of trees, pulsing forth life.
The sun returns to the Northern Hemisphere, erasing the snows of winter to reveal a browned earth eager to green and ripen under the freshening rains and solar warmth.
If one can claim a heart to Christianity, it would be its drive toward life. God is revealed as the creator of life. Jesus Christ is the way, the truth and the life. The Holy Spirit is the giver of life. We are called to life in the Spirit.
The Easter Triduum celebrates the deepest mystery of creation – that at the heart of creation, of all reality, is the pulsing b
eat of life. A brutal instrument of death is transformed into the tree of life. Jesus Christ, lifted up on the cross, becomes the sign of life for all creation. Conversion is possible. Death has lost its sting.
On Easter Sunday we not only celebrate the resurrection of Jesus Christ; we celebrate, as well, the resurrection of creation. Resurrection of the God-Man prefigures the resurrection of creation. Resurrection of Christ is the beginning of the divinizing transformation of all things – the beginning of the ontological transformation of the entire creation.
Because of Easter, the heart of all matter is "resurrectional." In other words, at the heart of creation is this relentless urging towards life. Deep within matter lies this hidden spark of life, resurrected life. Matter has self-transcended into life, life into conscious life, conscious life into human life, human life into Christic life.
Christ is the radical self-transcendence of the created universe into God. In the Paschal Mystery of Easter, evolutionary history gives itself into God and is taken up and transformed in God, as the beginning of the reconciliation and transformation of all things in God.
At Easter we proclaim that Jesus Christ is risen. In the same breath we proclaim that all of creation is risen as well. Death is not the final word of the world. Death is not the final word of our lives. A new heaven and a new earth await.
Life is the thrust of creation. Resurrection is the fullest meaning of creation. Today we celebrate Life and Resurrection. Christ is Risen: Alleluia, Alleluia!