"The spoiler commences: Yes, night does fall on the planet, every once in a long while when all three suns are in eclipse. I am not sure what complex geometries of space and trajectory are necessary for a planet to exist in a three-star system and somehow manage to maintain any continuity of climate and temperature, but never mind: What is maybe more difficult to accept is that it would develop a life form that appears only in the dark. Since sunlight is the source of heat and energy, Darwinian principles would seem severely challenged by the task of evolving living things that hibernate for 22 years between eclipses. How does a thing that lives in the dark evolve in a planet where it is almost always daytime? This is not the kind of question you're supposed to ask about "Pitch Black," but I'd rather have the answer than any 45 minutes of this movie. The story also poses the problem (less challenging from a Darwinian view, to be sure) of whether the Diesel character will cooperate with his species mates or behave entirely like a selfish gene. Whether this happens or not I leave it to you to discover. By the end of the movie, however, I was wondering if the trip had been necessary; most of the plot could be ported into a Western or a swashbuckler with little alteration."