Martian colony administrator threatens a Martian child. The Martians demand that the humans leave Mars, but a human doctor convinces them to reconsider. In Heinlein's 1956 novel "Double Star", humans have colonized the solar system, and a politician on Mars faces the civil rights issue of granting a native Martian species (who are second-class citizens) the right to vote. In Philip K. Dick's novel "Martian Time-Slip" (1964), a human colony on Mars is trying to cope with arduous environmental conditions. They treat an aboriginal race, whom they call "Bleekmen", with casual racism. In "The Three Stigmata of Palmer Eldritch" (1965), Mars
Fictional planets of the Solar System fragments of a single planet was gradually abandoned over the course of the middle decades of the 20th century in favor of the conclusion that no planet had ever accreted in the region of the asteroid belt in the first place. In fiction, various other names were given to the same or similar concepts. Fictional planets in our Solar System beyond the orbit of Neptune have been employed many times as settings or references in science fiction. Following the general reception of Pluto as the ninth planet of the Solar System in 1930, a hypothetical additional planet was sometimes called