The Feast of the Ascension, also known as Ascension Thursday, Holy Thursday, commemorates the bodily Ascension of Jesus into heaven. It is one of the ecumenical feasts (ie. universally celebrated) of Christian churches, ranking with the feasts of the Passion, of Easter, and Pentecost.
In the Catholic church it is also known as the The Ascension of the Lord. Ascension Day is traditionally celebrated on a Thursday, the fortieth day of Easter (following the count given in Acts 1:3), although some Catholic provinces have moved the observance to the following Sunday.