By the 1920s, the combustion hypothesis was superseded by the notion that the Sun was fuelled by nuclear fusion, pioneered by astrophysicist Arthur Eddington. As a result, science fiction authors started incorporating much longer solar lifespans in their stories, with J. B. S. Haldane's 1927 essay "The Last Judgment" and Olaf Stapledon's 1930 novel Last and First Men both outlining the future evolution of humanity throughout millions of years of variation in solar luminosity. Stories depicting the Sun waning nevertheless kept appearing, such as Clark Ashton Smith's stories about the fictional future continent Zothique starting with the 1932 short story "The Empire of the Necromancers", and Jack Vance's Dying Earth series starting with the 1950 anthology The Dying Earth which also gave its name to the dying earth subgenre of science fiction. Nat Schachner's 1934 short story "When the Sun Dies" describes the entire Earth freezing over in the 1980s as a result of a reduction in solar activity, and in Arthur C. Clarke's 1949 short story "History Lesson", future Venusians find humanity extinct due to the environmental changes brought about by the Sun fading. Clarke also touched upon the subject in the 1938 poem "The Twilight of the Sun" and the 1979 novel The Fountains of Paradise. In a variation on the theme, Fritz Leiber's 1951 short story "A Pail of Air" depicts Earth having been pulled away from the gravitational influence of the Sun and thus turned into a rogue planet, with a climate so cold that air has frozen and needs to be collected and thawed to turn it gaseous and breathable. Edmond Hamilton's 1934 short story "Thundering Worlds" sees all the planets leaving the Solar System to find a new star as the Sun dies, while his 1963 comic book story "Superman Under the Red Sun" depicts Superman travelling into the far future and losing his superpowers as a result of the aging red Sun. Eric C. Williams' 1965 short story "Sunout" depicts scientists reacting to the realization that the Sun is about to go out and they are powerless to do anything about it. In the 2019 film The Wandering Earth, the death of the Sun prompts humanity to relocate the entire Earth to a new solar system.
