What was the name of C.S. Lewis’s science-fiction trilogy about interplanetary travel?

C.S. Lewis’s science-fiction trilogy about interplanetary travel is called the Space Trilogy.

The trilogy consists of Out of the Silent Planet, Perelandra, and That Hideous Strength. The books follow the philologist Elwin Ransom through encounters involving Mars, Venus, and Earth. Lewis combined planetary adventure with philosophical, theological, and literary ideas, creating a work that differs sharply in tone from the Narnia books.

The first volume, Out of the Silent Planet, was published in 1938. Perelandra followed in 1943, and That Hideous Strength appeared in 1945. The three novels are also commonly called the Ransom Trilogy, after their central character, and sometimes the Cosmic Trilogy. “Space Trilogy” is the broadest conventional title for the set.

Lewis wrote the books during a period when popular science fiction often emphasized technological progress and space exploration. His trilogy instead asks moral and spiritual questions about humanity’s relationship with knowledge, power, and other worlds.