Ascension of Jesus
According to the New Testament, the Ascension of Jesus happened at the end of Jesus' life on earth. The Acts of the Apostles says that after Jesus told his apostles to teach the gospel to everyone, he went up to heaven to be with God.The Apostles' Creed says that Jesus "ascended into heaven and is seated at the right hand of God the Father". There He is praying for those who believe in Him. 
Ascension Day is often celebrated on a Thursday, the fortieth day of Easter, although some Christian denominations have moved the observance to the following Sunday.