Terrestrial planet Terrestrial planet A terrestrial planet, telluric planet, or rocky planet is a planet that is composed primarily of silicate rocks or metals. Within the Solar System, the terrestrial planets are the inner planets closest to the Sun, i.e. Mercury, Venus, Earth, and Mars. The terms "terrestrial planet" and "telluric planet" are derived from Latin words for Earth ("Terra" and "Tellus"), as these planets are, in terms of structure, "Earth-like". Terrestrial planets have a solid planetary surface, making them substantially different from the larger giant planets, which are composed mostly of some combination of hydrogen, helium, and water existing in various
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