The Land and Overland trilogy is a group of three science fantasy novels by Northern Irish writer Bob Shaw.
The trilogy consists of the books The Ragged Astronauts (published in 1986), The Wooden Spaceships (1988) and The Fugitive Worlds (1989).
Much of the human population of Land travels to Overland via hot-air balloon to escape airborne creatures called the Ptertha.
The inhabitants of Overland manage to defeat them by erecting a network of fortresses between the two planets.
Orson Scott Card reviewed the first volume favourably, saying "The Ragged Astronauts is what an 18th-century hard-sf novel might have been, if Swift or Defoe had paid more attention to Newton.