Fictional planets of the Solar System a "tenth planet". Since 1992, a very large number of objects have been found beyond Neptune; all the objects in the following list, however, are purely fictional. Common names for trans-Neptunian planets in fiction include Planet X, after a planet once believed to lie beyond Neptune, and Persephone (or Proserpina), after the wife of Pluto. Rogue planets in fiction usually originate outside the Solar System, but their erratic paths lead them to within detectable range of Earth. In reality, no rogue planet has ever been detected transiting the Solar System. Fictional planets of the Solar System The fictional portrayal of
Pioneer Terra of a probe and orbiter to Venus. Pioneer Terra Pioneer Terra is a region on the dwarf planet Pluto, north of Tombaugh Regio and east of Voyager Terra. It was discovered by the "New Horizons" spacecraft on 14 July 2015. It is named for the "Pioneer" program, which included "Pioneer 10" and "Pioneer 11", the first spacecraft to cross the asteroid belt and explore Jupiter and Saturn, as well as the first to explore the outer solar system; "Pioneer 6, 7, 8, and 9", which formed an "interplanetary weather network"; "Pioneer 1" through "5", which explored the Moon in various