Terrestrial planet

As an Earth-like planet, terrestrial planet, telluric planet or rocky planet those celestial bodies are known in astronomy and planetary science, are the same in structure to the earth: they consist entirely or almost entirely of solid components and usually have a shell structure: in the center there is an iron core, above a thick layer, the so-called mantle of silicates and oxides, and at the top a thin crust, which also consists of silicates and oxides, but is enriched in elements that can not be incorporated into the mantle rock and sweated with the times " " (for example, potassium, rare earths, uranium). In some cases, closes over the crust an atmosphere, and the earth is still the hydrosphere ( oceans, lakes ... ) in between. Furthermore, similar diameter and mass but especially the average density, which the earth. The latter moves roughly between 4-6 g / cm ³.

Historically include only the four planets of the inner solar system in the group of terrestrial planets: Mercury, Venus, Earth and Mars. Meanwhile include planetary scientists but also - if not a planet - the similarly constructed Earth's Moon, Jupiter's moons Io and Europa, as well as the larger icy moons such as Ganymede, Callisto, Titan and Triton do so. In the latter icy moons Namely, the iron core is missing, and an ice mantle take the place of a silicate mantle, but the basic description of these icy moons, its origin and development similar to those of the classical models very. Also, the dwarf planet Ceres and the large differentiated asteroid Vesta may be classified in this group.

Due to the lack of precision and efficiency of the measurement process, it is difficult to detect extrasolar planets an Earth-like nature. The 2009 discovered extrasolar planet CoRoT -7 b has, according to current radii and mass measurements, a mean density of about 1.7 to 9.3 g / cm ³. This is likely that it is a terrestrial planet and no gas giants, even if there are no measurements on the internal structure. It is assumed that many more extrasolar planet with a terrestrial structure exist ( for some candidates, see the list of super-Earths ).

In the theory of extrasolar planets and the science fiction literature another, stricter interpretation is often applied: here is meant by terrestrial or Earth-like planets, that there is a significant and perhaps life-friendly atmosphere and plenty of water.

In contrast to the terrestrial planets are called the gas giants Jupiter -like or jovianisch.