What was the name of C.S. Lewis's first published novel in the Ransom Trilogy?

Out of the Silent Planet was C.S. Lewis's first published novel in the Ransom Trilogy.

The novel appeared in 1938 and introduced the philologist Elwin Ransom, who is abducted and taken to Malacandra, Lewis’s name for Mars. The story combines space travel, Christian ideas, linguistic speculation, and Lewis’s opposition to the darker forms of modern scientific ambition.

The two later books are Perelandra, published in 1943, and That Hideous Strength, published in 1945. Together, the three novels are often called the Cosmic Trilogy or Ransom Trilogy. Although the books share characters and themes, each has a different setting and narrative focus.

Readers sometimes confuse Out of the Silent Planet with Perelandra because both are planetary science-fiction novels. Out of the Silent Planet is the opening volume; Perelandra moves Ransom to Venus, while That Hideous Strength is set mainly on Earth.