 The Feast of the Ascension is a major feast day of the Christian liturgical year, along with the Passion, Easter, Pentecost, and Christmas.Ascension Day is traditionally celebrated on the sixth Thursday after Easter Sunday, the fortieth day from Easter day, although some Roman Catholic provinces have moved the observance to the following Sunday to facilitate the obligation to attend Mass.Saint Jerome held that it was of apostolic origin, but in fact the ascension was originally part of Pentecost (the coming of the Holy Spirit), and developed as a separate celebration only slowly from the late 4th century onward.