Therefore Easter is not simply one feast among others, but the “Feast of feasts,” the “Solemnity of solemnities,” just as the Eucharist is the “Sacrament of sacraments” (the Great Sacrament). St. Athanasius calls Easter “the Great Sunday” and the Eastern Churches call Holy Week “the Great Week.” The mystery of the Resurrection, in which Christ crushed death, permeates with its powerful energy our old time, until all is subjected to him. [CCC 1169]
THE ASCENSION OF THE LORD, as of 2001, has been transferred from the Fortieth Day after Easter, a Thursday, to the following Sunday, the Seventh Sunday of Easter. This was done by most bishops of the United States with permission of Pope John Paul II to highlight the meaning of the mystery of the Ascension, a meaning that might be eclipsed by the unfortunate tendency of a growing number of our people who fail to come and celebrate the Liturgy on Thursday, a weekday and a workday in our secular calendar.
ASCENSION OF THE LORD - The Thursday of the Sixth Week of Easter has traditionally been celebrated as the Feast of the Ascension. Presently many dioceses have transferred this feast to the Seventh Sunday of Easter so that it can more easily be celebrated by all. When celebrated on that Thursday, it marks the beginning of a novena that concludes with the feast of Pentecost. During this time we emphasize preparation for the coming of the Holy Spirit at Pentecost. The hymn "Veni, Creator Spiritus" can be used each day. In former times some parishes extinguished the Paschal Candle with great solemnity to symbolize the departure of the Lord to the right hand of the Father. Now, it remains near the altar and ambo until the conclusion of the feast of Pentecost, when it returns to its place near the Baptistery.
Regarding the Ascension of the Lord, the ecclesiastical provinces of Boston, Hartford, New York, Newark, Omaha, and Philadelphia have retained its celebration on the proper Thursday, while all other provinces have transferred this Solemnity to the Seventh Sunday of Easter.