50 When he had led them out to the vicinity of Bethany, he lifted up his hands and blessed them.
51 While he was blessing them, he left them and was taken up into heaven.
The Feast of the Ascension of the Lord or of Jesus celebrates the bodily ascension of Jesus Christ into heaven. Alongside the Passion, Easter, Pentecost and Christmas the Feast of the Ascension is one of the major feast days of the Christian Liturgical year.
As early as the fourth and fifth centuries the celebration of this day was widely known throughout Christendom. Eusebius writes about the celebration in his fourth century writings while Saint Augustine wrote that the feast was of Apostolic origin and that the Church universally celebrated the feast well before he became Christian. Saint John Chrysostom and Saint Gregory of Nyssa both wrote at length regarding the celebration. Diptychs and Fescoes from the early fifth century have also been found with representations of the Ascension.
The three days leading to the Feast of the Ascension are known as Rogation days. During these three days the faithful typically fast and perform abstinence in preparation of the Feast. Violet vestments are worn during the rogation litany and its associated mass.
The Ascension of the Lord is a Solemnity and is considered a Holy Day of Obligation in the Roman Catholic Church. The earliest possible date is April 30th and the latest possible date is June 3 (in 2021 this date is May 13th, in 2022 May 26th). In countries in which the Feast is not a public holiday the Vatican allows for the observance to be moved from the traditional Thursday forward to Sunday. Australia made the switch to Sunday in 1992 and Ireland in 1997. Parts of the United States celebrate it still on the traditional Thursday while other portions celebrate on Sunday now.