One of the main types of habitats of the Culture, an orbital is a ring structure orbiting a star as would a planet. Unlike a Ringworld or a Dyson Sphere, an orbital does not enclose the star (being much too small). Like a ringworld, the orbital rotates to provide an analog of gravity on the inner surface. A Culture orbital rotates about once every 24 hours and has gravity-like effect about the same as the gravity of Earth, making the diameter of the ring about 3,000,000 km, and ensuring that the inhabitants experience night and day. Orbitals feature prominently in many Culture stories.