Fictional planets of the Solar System 40 Eridani A. Counter-Earth was a hypothetical planet sharing an orbit with Earth, but on the opposite side of the Sun (hence Earth and Counter-Earth would always be invisible to each other). The idea of a counter-Earth has never been a serious scientific hypothesis in modern times. Phaëton is a name given to a supposed planet existing in the past between the orbits of Mars and Jupiter, which no longer exists, having become the Solar System's asteroid belt. Proposed not long after the discovery of multiple asteroids at the beginning of the 19th century, the idea that the asteroids were
Tempe Terra Tempe Terra Tempe Terra is a heavily cratered highland region in the northern hemisphere of the planet Mars. Located at the northeastern edge of the Tharsis volcanic province, Tempe Terra is notable for its high degree of crustal fracturing and deformation. The region also contains a large number of small shield volcanoes, lava flows, and other volcanic structures. The region is named after the albedo feature "Tempe," first used by astronomer E.M. Antoniadi in 1930 to describe a bright patch of terrain centered near 40°N, 70°W. The name comes from the Vale of Tempe, a valley located south of Mount