Which C.S. Lewis novel is set largely on the planet Mars?

C.S. Lewis’s novel set largely on Mars is Out of the Silent Planet. Published in 1938, it is the first book of Lewis’s Space Trilogy, also called the Cosmic Trilogy.

The story follows Dr. Elwin Ransom, a Cambridge academic who is abducted and taken to Mars, known in the novel by the name Malacandra. There he encounters intelligent species and learns that humanity’s understanding of other worlds is distorted by fear, violence, and isolation.

The book combines planetary adventure, philosophical speculation, Christian themes, and linguistic invention. Lewis used the novel to challenge the popular science-fiction idea that extraterrestrial contact would necessarily involve conquest or warfare. Its setting is fictional, although the Mars of the story reflects early twentieth-century astronomical ideas rather than current planetary science.

The two later novels are Perelandra, set on Venus, and That Hideous Strength, set mainly on Earth. Their titles are therefore not interchangeable with the Mars novel.