"There's no doubt," said Russ, "that the Sun-tapper culture and the Plutonian culture are the same. It's the descendants of the Plutonians that we are fighting."
"But how could they have survived?" Burl asked. "This world was never part of the solar system when it was warm."
"We'll soon know," said Russ. "Tomorrow we're going to see how far we can get into their polar redoubt. Somehow we've got to blow up that last station."
"And I think we three are going to do it," said Haines. "The Magellan will never take the place from the sky. We'll have to do it from the ground."
Now they were reminded of Earth again. For the first time since they had departed from the United States, night fell. They had not been on any other planet long enough for such an experience. But the effect here on Pluto was mild.
Day was like a bright, moonlight night. Night then meant that the dim Sun had set and, in effect, it merely made the landscape slightly darker.
They compared notes late into the night in the rocket plane. By dawn, when again the dim glow shone, they had come to some very definite conclusions about the planet.
A number of the drawings on the walls seemed to have some religious significance. They focused on the phases of a moon. There were symbolic representations of this moon, passing through its phases; presumably Plutonian religious and social practices were related to it.
"But where is this moon?" Burl had asked.
"I think," Russ answered, "that what some astronomers had suspected about Pluto was right. It did not originate in the solar system, but was captured from outer space. Originally it revolved around another sun, some star which was light-years away. How it tore loose from that star we'll probably never know—the star might have simply become too dim, their planet might have been on a shaky orbit, an experiment of theirs might have jarred it loose, many things could have happened.