It is common for people to give up on the Ascension. ("Where did he go? There are just planets and stuff 'up' there.") But we could let the Ascension speak out of a thicker sense of reality than that, and not dismiss the ancients as pre-secientific simpletons and drongos. (For those reading from a non-Australian background, 'drongo' is an Australian term for 'fool'.)
Thirty years ago I tried a spiritual experiment. I rose early each day for three months and meditated for an hour. At the end of the three months I experienced a deep silence for a couple of seconds until I tried to claim it ("I've done it!"), and then it was gone. I describe it as a deep silence, but that doesn't do the experience justice. It was deeper than that, but I can't really think of a better word than silence to describe the experience. Undoubtedly bits of wires stuck to various parts of my head might have told us what was going on in my brain at the time, but that wouldn't suffice as an explanation or even complete description of the experience. (Reductionism in the guise of a complete explanation is like that: inadequate.)
Maybe 'ascend' is like 'silence' above. Maybe 'ascend' is a good word for something much deeper and more profound than is captured by the common use of the word. Yes, Jesus ascended, but that just doesn't capture the experience. It was much more than that. Way deeper than just 'up'.
Is Jesus ascending and therefore leaving us? Yes. And is ascension also creation being drawn into God? Yes. Such that now the presence of the God who is present to all creation (i.e. transcendent) is now imprinted with the death and resurrection of Jesus. Ascension is just as much about ascending away as it is about ascending into, about Jesus' absence from us, as our journey with him.
"I will not leave you orphaned. I am coming to you. In a little while the world will no longer see me ... I have said these things to you while I am still with you. But the Advocate, the Holy Spirit, whom the Father will send in my name ... "
And here is an Ascension kid's talk for church.
And here is a poem on the Ascension, from Barb, a local Anglican priest.