From where he’s hiding, Christopher can see the constellation Orion. Supposedly Orion looks like a hunter with his weapons, but Christopher points out that the stars could be joined up to make any figure someone wanted. Constellations are completely subjective, based on people’s imaginations. The real truth is that Orion is just a bunch of stars, which are just nuclear explosions.
Christopher again exhibits his ability to think outside of conventional constructions. Constellations are stories that people imagine; when he strips them down to the scientific truth, they’re only chemical reactions. However, it’s impossible for him to strip his own life down to a scientific truth, even though he’d probably like to, because people are simply not logical.