Luna or the Moon is the terrestrial moon. However several of the worlds described in science fiction works are not planets per se but the instead the terrestrial or Earth-like moons of true planets. Usually the planets these terrestrial moons orbit are Gas Giants, as in the case of Allen Steele's Coyote or Isaac Asimov's Erythro. One interesting exception is Ursulla K. LeGuin's Anarres, which orbits a terrestrial planet.