Earth

The earth is the third planet from the sun, the fifth largest planet and the densest major body in solar system. It is the only planet known to have life. In proportion to its size it as largest moon in the solar system.

The word Geography (Ge means Earth in ancient Greek and grapy means writing) which means study of all the natural and human aspects of earth.

Earth is one of the four solar Terrestrial planets .Planets with a rocky body rather than gases are called terrestrial planets. Jupiter is a gas planet.

Chemical composition:

The mass composition of earth is approximately 5.98*1024kg.

It is made up of approximately 100 elements of which iron, oxygen, silicon, magnesium, sulphur, nickel, calcium and aluminum are the main constituents.

Shape:

Earth is a sphere lightly squished at the poles and bulging at the Equator. So if you drew a line across the Equator, and a line between the poles, the line around the Equator would actually be 43Km longer.

Therefore Earth is not a perfect sphere and is termed on

Oblate spheroid. This is caused by rotation of Earth.

That average diameter of Earth is 12,742Km.

Internal Structure of Earth:

Plate Tectonics:

The outer layer of Earth called Lithosphere,is broken into vast pieces known as tectonic plates. These plates are at the same place, but shift at the boundaries, causing earthquakes, volcanic activity, and Mountain building and trench formation under the sea. The Himalayas are the best example for mountain building.

Surface:

About 70.8% of the Earth’s surface is covered in water. There is a lot of physical features in this submerged surface, such as longest mountain ranges in the world, volcanoes, trenches, canyons, oceanic plateaus and plains. This is known as Hydrosphere.

The remaining 29.2% is covered in mountains, deserts, plains, plateaus, and other features. This surface undergoes constant changes due to the effect of plate tectonics and erosion.