Poul Anderson 
World Without Stars 

When the starship Meteor crash-landed on a strange world orbiting a solitary sun in the vast darkness outside the galaxy, her crew of Earthmen had no idea of what to expect. The planet was Earthlike in gravity, air, animal and vegetable life — but what of the native races they glimpsed from a distance?What kind of culture would evolve on a planet whose sky was dominated by the glow of an entire galaxy — and with no other stars save its own dim sun? What kind of gods would they worship?The Earthmen had to find the astounding answers to these questions on a planet split by a world-wide war.