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
International Year of Planet Earth support from individuals and organisations worldwide. The Year's Project Leader was former IUGS President Professor Eduardo F J de Mulder. The Year's Science Committee was chaired by Professor Edward Derbyshire (Royal Holloway) and its Outreach Committee by Dr Ted Nield (Geological Society of London). The International Year of Planet Earth project was initiated jointly by the International Union of Geological Sciences (IUGS) and the United Nations Educational Scientific and Cultural Organisation (UNESCO). The UN press release reads: "By a draft on the International Year of Planet Earth, 2008, which the Committee approved without a vote on 11 November, the Assembly