Leslie F. Stone 
When the Sun Went Out [EPUB ebook] 

As the dying Sun sputters its last rays of light over a frozen Earth, young astronomers Kuila and Ramo join the remaining humans descending underground. Though their people decayed into complacency as resources dwindled, Kuila and Ramo found companionship admiring the stars and dreaming of worlds with warmth and light. Now facing a dark future burrowed deep below the ice, they cling to hopes of rediscovering their ancestors’ knowledge and one day traveling to a new home planet orbiting a brilliant new Sun. Will their vision spur humanity’s rebirth or fade to black like the guttering Sun that once nurtured their dying Earth?