The Black Cloud
 In 1964, astrophysicists on Earth become aware of an immense cloud of gas that is heading for the solar system. The cloud, if interposed between the Sun and the Earth, could wipe out most of the life on Earth by blocking solar radiation and ending photosynthesis. A cadre of astronomers and other scientists is drawn together in Nortonstowe, England, to study the cloud and report to the British government about the consequences of its presence. The cloud decelerates as it approaches the Sun (contrary to physical laws) and comes to rest around the Sun, causing disastrous climatic changes on Earth and immense mortality and suffering for the human race. This section of the novel presages the nuclear winter scenario popularised in the 1980s. As the behaviour of the cloud proves to be impossible to predict scientifically, the team at Nortonstowe eventually come to the conclusion that it might be a life-form with a degree of intelligence. In an act of desperation, the scientists try to communicate with the cloud, and to their surprise succeed in doing so. The cloud is revealed to be a superorganism, many times more intelligent than humans, which in return is surprised to find intelligent life-forms on a solid planet. When the astronomers ask the cloud how its lifeform originated, it replies that they have always existed. One of the characters suggests this is incompatible with the Big Bang theory. Thus it may be that Hoyle was hinting at his own Steady State theory of the existence of the Universe, which most cosmologists consider disproved by the discovery of cosmic background radiation. The cloud then learns that another intelligent cloud has stopped communicating and may have mysteriously vanished, not so far away in space in the cloud's terms, so it decides to move on, relieving Earth's suffering. Two of the scientists die in an attempt to learn some of the cloud's vast store of knowledge through visual signals, in order to gain further insights about the Universe.