Moons of Neptune is the most lopsided of the satellite systems of the giant planets in the Solar System. One moon, Triton, makes up nearly all of the mass of the system, with all other moons together comprising only one third of one percent. This is similar to the moon system of Saturn, where Titan makes up more than 95% of the total mass, but is different from the more balanced systems of Jupiter and Uranus. The reason for the lopsidedness of the present Neptunian system is that Triton was captured well after the formation of Neptune's original satellite system, much of which
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