Your newborn will not be able to see more than 6 inches in front of his face for quite some time, and even when he does, he will have no idea what the heck he's looking at. Nursery walls are decorated for parents, not children. You want your son to get acquainted with universe? Invest in some good books and haul them out when he's three. Read to him for 15-30 minutes each night and let him looks at the pictures. In the meantime, paint the walls a soft green.