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
History of Solar System formation and evolution hypotheses a solution to the angular momentum problem and does not explain lunar formation nor other very basic characteristics of the Solar System. The Weizsäcker model was modified in 1948 by Dutch theoretical physicist Dirk Ter Haar, in that regular eddies were discarded and replaced by random turbulence which would lead to a very thick nebula where gravitational instability would not occur. He concluded the planets must have formed by accretion and explained the compositional difference (solid and liquid planets) as due to the temperature difference between the inner and outer regions, the former being hotter and the latter being cooler,