The Sentinel was published as a collection by Berkley Books in 1983. The title story — originally written in 1948 for a BBC competition (it lost) and first published in 1951 as “Sentinel of Eternity” — describes a geologist on a lunar expedition who discovers a crystalline pyramid on the Moon, clearly of artificial origin. The structure has been broadcasting a signal into deep space for millions of years. When humans find it and breach its force field, the signal stops — the sentinel has served its purpose. Something out in the galaxy now knows that humanity has evolved enough to reach the Moon.
Stanley Kubrick read the story in 1964 and contacted Clarke; their collaboration on developing the concept produced both the film 2001: A Space Odyssey and Clarke’s novelization. “The Sentinel” became the monolith — the lunar alarm system that alerts the builders that a species has achieved space travel.
Collecting The Sentinel
First edition (Berkley Books, New York, 1983): Mass market paperback original.
Market values:
- First printing, near fine: $15–$40
- Signed copies: $100–$200