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
Sun Dutch "zon", Old High German "sunna", modern German "Sonne", Old Norse "sunna", and Gothic "sunnō". All Germanic terms for the Sun stem from Proto-Germanic *"sunnōn". The Latin name for the Sun, "Sol", is used at times as another name for the Sun, but is not commonly used in everyday English. "Sol" is also used by planetary astronomers to refer to the duration of a solar day on another planet, such as Mars. The related word "solar" is the usual adjectival term used for the Sun, in terms such as solar day, solar eclipse, and Solar System. A mean Earth solar