The Earth is one of 9 planets of the Solar system, the only one on which the life has been developed. The main characteristics are the presence of an atmosphere, an intense magnetic field and a satellite of great dimensions (the Moon).

Our planet is not a sphere, but an ellipsoid crushed to the poles and swollen to the Equator. This shape has been caused from the movement of spin of the planet. For further precision one says that the Earth is a geoid.

Structurally the Earth is formed from concentric layers of materials of varied kind. These layers are, leaving from the external part:

- the land crust, that has a thickness until approximately 33 Km and is formed mainly from silicon, magnesium (oceanic crust) and aluminum (continental crust)
- the mantle, divided in advanced mantle (until the 700 Km of depth) and inferior mantle (until 2900 Km). The main material is the magnesium.
- the core, also it divided in outside and inside. The external core is liquid and it is thought is formed in prevalence from iron, beyond to nichel and other lighter materials. In the inner part the materials (iron and nichel) are to the solid state, because of the great overhanging pressure.

Principal Astronomic Data   Average distance from Sun (milion of Km): 149,6   Revolution period: 365,26 days   Rotation period: 23 hour, 56 minutes, 4 seconds   Axis inclination: 23°27'   Equatorial diameter (Km): 12.756   Average temperature: 22 °C

The total area of Earth is 510.300.000 Kmē. 360.700.000 Kmē it's the area of Oceans, whereas 149.600.000 Kmē it's of the land. At political level there are 194 Countries, subdivided in 6 continents. There are moreover the Antarctica, this land is totaly covered by the ice and it isn't permanently inhabited.

Population: 6.081.000.000 (estimates June 2000)
Density: 41 ab/Kmē

The most populated City: Tokyo (29.870.000 pop.)
The higher Mountain: Everest 8850 m
The maximum Depression: Dead Sea -408 m
The maximum Depth: Mariana Trench -10.924 m
The longer River: Nile 6671 Km
The greater Lake: Caspian See 371.000 Kmē
The greater Island: Greenland 2.130.800 Kmē

Index A-Z of Countries

Principal Mountains
Principal Islands
Principal Rivers
Principal Lakes

Major Cities
Order of Area, Population, Density
Demographic statistics

GDP per capita
Human Development Index