The story is set at the fictional neutron star Levoy's Star (abbreviated "Voy"). The gas giant Goldblatt's World (abbreviated "Gold") orbits the star just outside its Roche limit. While Gold's gravity is enough to keep it from being pulled apart by Voy's tidal forces, it is insufficient to hold its atmosphere, which has been pulled loose into an independent orbit around Voy. This orbiting air forms a ring known as a gas torus. The gas torus is huge—one million kilometers thick—but most of it is too thin to be habitable. The central part of the Gas Torus, where the air is thicker, is known as the Smoke Ring. The Smoke Ring supports a wide variety of life. Robert L. Forward helped Niven calculate the parameters of the ring.