Sail to the Moon. (Brush the Cobwebs Out of the Sky.)

yea, just to elaborate on the point made by 'nobody', the song is, in my opinion, definately about his son, Noah and the fact that they will try and teach him 'right from wrong' while he's young so that they can look after him, but then, as Thom and his partner grow old Noah will look after them, hence, 'building them and ark and sailing them to the moon.'