. "almost to the day" - He remembers the exact day - it's an important memory
. "new-ruled" - New boundaries are also being drawn between father and son, with the son's newfound independence
. "like a satellite", "go drifting" - Negative simile - a satellite isn't meant to fall out of orbit, and to drift away makes the son sound helpless and in danger. The simile also emphasises how the father has stopped being at the centre of his son's life
. "God alone could perfectly show" - Religious imagery - in the Bible, God let go of Jesus, his only son, when Jesus came to Earth and was crucified. He did this to show humans that he loved them. That "God alone" could do it shows how difficult it is