Nightfall: Can Kalgash Exist
  We investigate the imaginary world of Kalgash, a planetary system based on the novel "Nightfall" (Asimov & Silverberg, 1991). The system consists of a planet, a moon and an astonishing six suns. The six stars cause the wider universe to be invisible to the inhabitants of the planet. The author explores the consequences of an eclipse and the resulting darkness which the Kalgash people experience for the first time. Our task is to verify if this system is feasible, from the duration of the eclipse, the "invisibility" of the universe to the complex orbital dynamics. 
Smaran Deshmukh and Jayant Murthy
physics.pop-ph