Ascension, name usually given to the departure of Jesus from earth as related in the Gospels according to Mark (16) and Luke (24) and in Acts 1.1-11. The annual commemoration of this is one of the principal feasts in most Christian churches. Ascension Thursday, as it is called, occurs on the 40th day after Easter, being the Thursday of the sixth week of Easter. In early English usage this festival was known as Holy Thursday.