The Ascension of Our Lord into Heaven is only recorded in Mark (the longer version) and Luke. The event is mentioned only briefly in both. Perhaps this was because Jesus had already bade farewell to his disciples at the Last Supper. Heaven is often pictured as somewhere in the sky. In Greek and Norse mythology, the gods live apart from human beings, on Mount Olympus and in Asgard respectively. God, however, is everywhere and does not separate himself from his people. The description of Jesus being taken in up into the clouds is imagery used to describe his glory and triumph, rather than his going to a distant place above. In fact, the Ascension should be regarded as a coming rather than a going, since he is now more present than he could be during his lifetime. It may also be that the evangelist is recalling Elijah being taken up in a chariot of fire, after passing on his mantle on to Élisha (Kings 2:2), and now in a similar way Jesus is passing his mantle on to his friends.
Jesus, the Word, had accomplished his work on earth and now his apostles would continue it with the guidance of the Holy Spirit. Even after they had encountered the risen Lord, they were still thinking that his mission was to restore the Kingdom of Israel. It would take time for them to come to the realisation that it would be very different.