Inner Earth

Earth
Third planet in distance outward from the Sun.
Art:Earth's interior may be identified in two distinct ways. In chemical terms, it has three basic …




Earth Inner

     * Earth's interior may be identified in two distinct ways.
 In chemical terms, it has three basic …Believed to be about 4.6 billion years old, it is some 92,960,000 mi (149,600,000 km) from the Sun. It orbits the Sun at a speed of 18.5 mi (29.8 km) per second, making one complete revolution in 365.25 days.
As it revolves, it rotates on its axis once every 23 hours 56 minutes 4 seconds.
 The fifth largest planet of the solar system.
 it has an equatorial circumference of 24,902 mi (40,076 km).
 Its total surface area is roughly 197,000,000 sq mi (509,600,000 sq km), of which about 29% is land. Earth's atmosphere consists of a mixture of gases, chiefly nitrogen and oxygen. I
ts only natural satellite, the Moon, orbits the planet at a distance of about 238,860 mi (384,400 km). Earth's surface is traditionally subdivided into seven continental masses:
. These continents are surrounded by four major bodies of water: the Arctic, Atlantic, Indian, and Pacific oceans.
Broadly speaking, Earth's interior consists of two regions: a core composed largely of molten, iron-rich metallic alloy; and a rocky shell of silicate minerals comprising both the mantle and crust (see also Moho; lithosphere). Fluid motions in the electrically conductive outer core generate a magnetic field around Earth that is responsible for the Van Allen radiation belts. According to the theory of plate tectonics, the crust and upper mantle are divided into a number of large and small plates that float on and travel independently of the lower mantle.
 Plate motions are responsible for continental drift and seafloor spreading and for most volcanic and seismic activity on Earth.

Core

In earth science, the part of the Earth that starts about 1,800 mi (2,900 km) beneath the surface and extends downward.
It consists largely of an iron-rich metallic alloy and is thought to have a two-part structure: an outer fluid region and a solid, extremely dense inner region that measures only about 1,500 mi (2,400 km) across. The alloy composition is mainly iron with small amounts of nickel.
This composition is deduced from the chemistry of iron meteorites that presumably came from the breakup of a planetary body that also had an iron core. See also crust; mantle.




Crust

crust

Outermost solid part of the Earth, essentially composed of a range of igneous and metamorphic rock types.
In continental regions, the crust is made up chiefly of granitic rock, whereas the composition of the ocean floor corresponds mainly to that of basalt and gabbro. On average, the crust extends 22 mi (35 km) downward from the surface to the underlying mantle, from which it is separated by the Mohorovičić discontinuity (the Moho). The crust and top layer of the mantle together form the lithosphere.

Mantle

Manlte

That part of the Earth that lies beneath the crust and above the central core.
On average, the mantle begins about 22 mi (35 km) below the surface and ends at a depth of about 1,800 mi (2,900 km). Predominant in the rock material are olivines, pyroxenes, and the silicate perovskite, a dense form of enstatite.


Lithosphere

lithosphere

Rigid, rocky outer layer of the Earth, consisting of the crust and the solid outermost layer of the upper mantle.
It extends to a depth of about 60 mi (100 km).
 It is broken into about a dozen separate, rigid blocks, or plates (see plate tectonics). Slow convection currents deep within the mantle, generated by radioactive heating of the interior, are believed to cause the lateral movements of the plates (and the continents that rest on top of them) at a rate of several inches per year.

Asthenosphere

asthenosphere

Zone of the Earth's mantle lying beneath the lithosphere, believed to be much hotter and more fluid than the lithosphere.
The asthenosphere is thought to extend from about 60 mi (100 km) to about 450 mi (700 km) below the Earth's surface.