Tharsis Montes Tharsis Montes The Tharsis Montes are three large shield volcanoes in the Tharsis region of the planet Mars. From north to south, the volcanoes are Ascraeus Mons, Pavonis Mons and Arsia Mons. Mons (plural "montes") is the Latin word for mountain; it is a descriptor term used in astrogeology for mountainous features in the Solar System. The three Tharsis Montes volcanoes are enormous by terrestrial standards, ranging in diameter from (Pavonis Mons) to (Arsia Mons). Ascraeus Mons is the tallest with a summit elevation of over , or base-to-peak. For comparison, the largest volcano on Earth, Mauna Loa in Hawaii,
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