The narrator speculates at one point that the mysterious aliens who left this structure on the Moon may have used mechanisms belonging 'to a technology that lies beyond our horizons, perhaps to the technology of para-physical forces.' The object is made of a polished mineral, is tetrahedral in shape, and is surrounded by a spherical force-field. The story deals with the discovery of an artifact on Earth's Moon left behind eons ago by ancient aliens. Clarke short stories, which includes the eponymous 'The Sentinel', 'Guardian Angel' (the inspiration for his 1953 novel Childhood's End), ' The Songs of Distant Earth', and ' Breaking Strain'. The Sentinel (published 1982) is also the title of a collection of Arthur C. Despite the story's initial failure, it changed the course of Clarke's career. It was subsequently published as part of the short story collections Expedition to Earth (1953), The Nine Billion Names of God (1967), and The Lost Worlds of 2001 (1972). 'The Sentinel' was written in 1948 for a BBC competition (in which it failed to place) and was first published in the magazine 10 Story Fantasy in its Spring 1951 issue, under the title 'Sentinel of Eternity'. Clarke, written in 1948 and first published in 1951 as ' Sentinel of Eternity', which was used as a starting point for the 1968 novel and film 2001: A Space Odyssey. ' The Sentinel' is a science fiction short story by British author Arthur C.

The sentinel by arthur c clarke