text: Fred Hoyle (1915-2001), a prominent astronomer at the Institute of Astronomy at Cambridge, is most well known for his theory of how chemical elements heavier than helium in our universe are manufactured within stars.  However, he is also remembered for his scientifically plausible fiction novels, the first of which “The Black Cloud” was published in 1957.  This novel describes the interaction of Earth scientists with an intelligent life form, an immense black cloud of gas that moves directly towards the solar system and temporarily obscures the sun.  When the black cloud detects radio signals from earth, it is surprised to discover that intelligent life can also exist on the surface of planets.    Although Fred Hoyle characterizes this novel as a “frolic,” he also notes that there is little in the novel that could not conceivably happen.  This novel is notable for raising, and providing a scientific rationale for the concept that the existence of “life” may not be constrained by the conditions that are ordinarily considered to be essential based on the singular example of life on earth.