The Ascension of the Lord was the going up into heaven of Christ by His own power, in the presence of the Apostles, the Blessed Mother and His disciples, forty days after His resurrection.
St. Thomas Aquinas asserts He ascended by the virtue proper to Him as God, and by that which belongs to a blessed spirit.
The feast commemorating the event was celebrated in the Church from the earliest times.
It is a holy day of obligation occurring on Ascension Thursday forty days after Easter.
Many dioceses in the United States, including the Diocese of Des Moines, have transferred the feast day to the Sunday following Ascension Thursday.