Out of the Silent Planet Robert McClenaghan writes, ""Out of the Silent Planet", the shortest and most straightforward of the [Space Trilogy] books, incorporates many of the elements of classic science fiction, including a space flight, meetings with fantastic aliens, and an extended depiction of another planet. Were it not for the theological backdrop (which comes into focus only toward the story's end), "Out of the Silent Planet" could pass as merely a well-written and exceptionally erudite pulp novel." John Gosling, on his website devoted to "The War of the Worlds", wrote that the novel "is a very well written and important piece of Martian
The Gods of Mars to Earth in pre-technological eras, particularly with the inclusion of kingdoms, empires or religious societies. Spacecraft may appear, but are not central to the story (something which makes these tales distinct from Space Opera, where spaceships are usually a key focus of the narrative). There were some Planetary Romances prior to the publication of the Barsoom novels, but "A Princess of Mars" and "The Gods of Mars" and other novels in the Barsoom series were the most influential on the numerous similar stories that were published subsequently. Burroughs's vision of Mars was loosely inspired by astronomical speculation of the time,