In C.S. Lewis’s Space Trilogy, the Martian inhabitants call Earth Thulcandra. The name appears in Out of the Silent Planet, where Earth is portrayed as the silent or isolated world among the planets known to the story’s inhabitants.
The novel’s Mars is named Malacandra, while Venus is called Perelandra. These names are easy to confuse because they belong to the trilogy’s invented planetary vocabulary. Thulcandra is specifically Earth, not Mars and not the title of a separate novel.
Lewis used the planetary setting to explore moral and theological themes rather than to provide a technical account of space travel. Elwin Ransom discovers that Earth’s history of violence and separation makes it unusual within the wider planetary community. The trilogy therefore treats astronomy as part of a larger imaginative map of good, evil, and human freedom.