Titan is a 1979 science fiction novel by John Varley. It is the first volume of a trilogy, followed by Wizard and Demon .

Plot synopsis

The novel deals with Captain Cirocco "Rocky" Jones and the crew of the Deep Space Vessel Ringmaster sent to investigate the rings of Saturn. They soon focus on Themis, one of the moons of Saturn, which turns out to be an enormous hollow wheel - like a space station.

Shortly after the start of the novel, the spaceship Ringmaster is ensnared and destroyed by Themis. The crew is captured and are eventually deposited onto the surface of the inside of Themis.

1,300 kilometers in diameter, the giant wheel rotates every hour, resulting in gravity a quarter of Earth's. The atmosphere is breathable. The interior is inhabited by a kaleidoscopic array of intelligent species, musical-genius centaurs, flying pseudo-harpies, and enormous blimp-like creatures. The most startling discovery, however, is that the wheel itself is alive and intelligent, calling itself Gaea - and that it's more than a little bit insane.