In C.S. Lewis’s Space Trilogy, Thulcandra is the fictional planet ruled by Ransom’s enemy and is the trilogy’s name for Earth.
The name appears within Lewis’s imagined cosmic geography, where different planets have spiritual and historical conditions. Malacandra is Mars, while Perelandra is Venus; those two names are central settings in the first and second novels.
Earth is portrayed as isolated from much of the wider harmony of the solar system. Its separation gives the trilogy a science-fiction framework while allowing Lewis to explore moral, theological, and philosophical questions.
A common mix-up is choosing Malacandra or Perelandra. Those are neighboring planetary names in Lewis’s fictional system, not the name assigned to Earth. Thulcandra is also the title of the third novel’s setting in the trilogy’s mythology.