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
Terra Mariana Terra Mariana Terra Mariana (Medieval Latin for "Land of Mary") was the official name for Medieval Livonia or Old Livonia (, , ), which was formed in the aftermath of the Livonian Crusade in the territories comprising present day Estonia and Latvia. It was established on 2 February 1207, as a principality of the Holy Roman Empire but lost this status in 1215 when proclaimed by Pope Innocent III as directly subject to the Holy See. Terra Mariana was divided into feudal principalities by Papal Legate William of Modena: After the 1236 Battle of Saule the surviving members of the