The Christian doctrine of the Ascension holds that Jesus' body ascended to heaven in the presence of his apostles following his resurrection, and that in heaven he sits at the Father's right hand. 
In the Letter to the Romans (c. 56-57), Paul describes Christ as in heaven and in the abyss,  the earliest Christian reference to Jesus in heaven. The most influential account of the Ascension, and the earliest, is in the Acts of the Apostles 1:1-11, where Jesus is taken up bodily into heaven forty days after his resurrection, as witnessed by his apostles.
In the Luke’s gospel, the Ascension takes place on Easter Sunday evening.  In 1 Peter, Jesus has ascended to heaven and is at God's right side.  The traditional ending of Mark (Mk16) includes a summary of Luke's resurrection material and describes Jesus as being taken up into heaven and sitting at God's right hand.  The image of Jesus rising bodily into the heavens reflects the ancient view that heaven was above the earth.
Christ's ascension occurs in the original Nicene Creed.  It is affirmed by Christian liturgy and, in the West, by the Apostles' Creed.  In terms of belief, the Ascension implies Jesus' humanity being taken into Heaven. 
We celebrate Ascension Day 40 days after Easter and is one of chief feasts of the Christian year. The feast dates back at least to the later part of the fourth century
But what is it about?  What is its significance for us today? Well it celebrates Agape – the great gift of charity. It is love that looks away from itself to another and gives itself away for another.  The Divine Word did not become man or endure the cross because something was in it for Him. Charity shares in the beloved’s joys and sorrows (John 14:28). 
Also another  thing to remember about the Ascension is that it is about sharing in Jesus’ joy.  It is about celebrating his return to the heavenly glory to which he refused to cling (Phil 2:6-11).  It is also a feast of hope.  Yes, there is something in it for us.  Jesius has gone to prepare a place for us (John 14:2).  We will also one day wear crowns made of gold instead of thorns.  At God’s right hand Jesus showers down his blessings upon us as we await our redemption and his return. In the meantime he promises us that he will send the Holy Spirit to guide us and lead us in his ways