Did Jesus literally ascend to heaven? In my view, the answer is, quite simply, no. Logically speaking, I think it makes no sense that it could have happened as described. As John Spong likes to point out, if Jesus had ascended at the speed of light, he would still be moving through space and he would not have even left our own galaxy. There is simply no way that the act of ascension would transport Jesus from earth to some heavenly realm outside of our current universe of space and time. The point, of course, is that the ascension story as depicted in the Bible presumes a three-tiered conception of the universe (heaven above the earth, then the earth, then the real of the dead below) that is incompatible with modern science. We know more about the universe than the New Testament authors did. And it makes sense to understand these biblical writings in that light.
In an online article on the subject, Marcus Borg points out that Luke actually presents two ascension stories that are mutually inconsistent with one another, thus suggesting that even that author didn't take the whole 40 days thing too seriously. He goes on to make the same general point that Spong has made:
What we do know, of course, is that heaven is not literally "up." Therefore, we legitimately cannot imagine Jesus literally moving upward into the sky on his way to heaven. Something else must be meant.Clearly the ascension story can only be appreciated for its deeper, non-literal value. As Borg puts it,
And so I turn to the rich metaphorical or symbolic meanings of the story of Jesus' ascension. For Christians in the past and now, it meant and means that Jesus is now with God, indeed "at God's right hand" and "one with God." These affirmations have two primary dimensions of meaning. Like the traditions of ancient Israel and Judaism, they are religious and political, spiritual and social.
First, Ascension Day proclaims the lordship of Christ. To say that the risen and ascended Jesus is "at God's right hand," a position of honor and authority, means "Jesus is Lord." In the first century, when kings and emperors claimed to be lords, this claim had not only religious but also political meaning. To say "Jesus is Lord" meant, and means, that the Herods and Caesars of this world were not, and are not.
Second, because the risen and ascended Jesus is "one with God," he (like God) can be experienced anywhere. Jesus is no longer restricted or confined to time and space, as he was during his historical lifetime. Rather, like the God whom he knew in his own experience, he continues to be known in the experience of his followers.
To use language from Matthew's Gospel, for Christians the risen and ascended Christ is Immanuel--"God with us."
In my view, the non-literal ascension represents the culmination of a non-literal resurrection in a mythological account. I believe that neither the physical resurrection stories, nor the ascension to heaven, were historical events that could have been recorded at the time by video cameras, had they existed. Both events can be appreciated for the deeper truths about the experience of Jesus after his death, as interpreted by his followers (which is to say that experience plus interpretation equals mystical religious faith). These metaphorical stories can convey something of the interpretation of this experience. The early followers of Jesus believed that through Jesus, God is with us. And that is the important point of the biblical message--not that these stories literally happened.