What fictional name did C.S. Lewis use for Earth in the Space Trilogy?

C.S. Lewis uses the fictional name Thulcandra for Earth in the Space Trilogy.

The name appears in Lewis’s planetary mythology, where Earth is known as the “silent planet.” In Out of the Silent Planet, the protagonist Elwin Ransom travels from Earth to Malacandra and learns how other worlds understand his home planet.

The trilogy’s other principal worlds include Malacandra, Lewis’s name for Mars, and Perelandra, his name for Venus. These names belong to the novels’ invented cosmology and are not the standard astronomical names used outside the fiction.

Lewis’s choice to make Earth the silent or spiritually isolated world reverses the usual science-fiction viewpoint. Instead of presenting humanity as the natural center of a populated universe, the books place human history within a much larger moral and cosmic setting.