Hadriacus Mons by a contact between magma and groundwater. "Hadriaca Patera", a term formerly used for the entire edifice, is now only used for the central caldera, which is in diameter. Hadriacus Mons Hadriacus Mons is an ancient, low-relief volcanic mountain on the planet Mars, located in the southern hemisphere just northeast of the impact basin Hellas and southwest of the similar volcano Tyrrhenus Mons. Hadriacus Mons is in the Hellas quadrangle. It has a diameter of . The name was approved in 2007. The flanks of Hadriacus Mons have been eroded into gullies; its southern slopes are incised by the outflow
Fictional planets of the Solar System Fictional planets of the Solar System The fictional portrayal of our Solar System has often included planets, moons, and other celestial objects which do not actually exist in reality. Some of these objects were, at one time, seriously considered as hypothetical planets which were either thought to have been observed, or were hypothesized in order to explain certain celestial phenomena. Often such objects continued to be used in literature long after the hypotheses upon which they were based had been abandoned. Other non-existent Solar System objects used in fiction have been proposed or hypothesized by persons with no scientific standing,