Dragon's Egg

In a moving story of sacrifice and triumph, human scientists establish a relationship with intelligent lifeforms--the cheela--living on Dragon's Egg, a neutron star where one Earth hour is equivalent to hundreds of their years. The cheela culturally evolve from savagery to the discovery of science, and for a brief time, men are their diligent teachers . . .

    

"Forward's book is a knockout. In science fiction there is only a handful of books that stretch the mind - and this is one of them!" - Arthur C Clarke