Jesus came from Nazareth in Galilee and was baptized in the Jordan by John. Immediately on coming up out of the water he saw the sky rent in two and the Spirit descending on him like a dove. Then a voice came from the heavens, "You are my beloved Son. On you my favor rests." (Mark 1:9-11)Why is it that it feels so natural to look up when we pray? Even Jesus did it on occasion (John 11:41), and He was in a position to know that Heaven isn't physically above "the heavens"! So what's the deal? Highly visual moments like Jesus' baptism and ascension remind us that Heaven is a "higher level" of being, but again; why the physicality of looking toward the sky?
My own theory? I'll warn you; it's not very complex...I think it has to do with little children looking and reaching up toward their parents. It's such a natural, and universal, gesture, a child's reaching out and up to his/her loving provider and protector. I think that this is tranferred to our interactions with God, quite naturally, and quite appropriately. He is our Father!