Stardance — Spider Robinson

A woman of perfect beauty is too big for perfect grace as a ballerina; she will never be more than an understudy. Stardance is the story of one such, one with the body of Venus di Milo and a talent greater than Pavlova's. But if there is an answer, genius will find it; Shara Drummond goes to Space, where her life is devoted to creating a weightless art form that is to Dance as three dimensions are to two.

Then the aliens arrive, beings of pure light who dance forever between the stars. And so it falls to Shara Drummond to prove that the human race is ...human. By her Stardance.