“The Earth is round”, you would probably answer without doubt, if asked about the shape of our planet.

But hundred years ago, people could only imagine or think about the shape of the Earth based only on their ground view or travel experiences.Among the many theories of many scientists, Aristotle’s theory stands out. This famous Greek philosopher believed in spherical earth. He had observed the Earth’s curved shadow during a lunar eclipse. Furthermore, observing with careful attention to details, he noted that the North Star changes position as one travels to the North or to the South.

Today, the Earth’s roundness is a fact. The Earth is an oblate spheroid and not a perfect sphere. It bulges at the equator and flattens at the pole.

The Earth is very large. Its circumference is about 40,000 km. can you imagine how big it is?

If you travel by jet plane day and night without stopping, it will take you 42 hours or about 2 days to go around the world. This is how big the Earth is.

Have you ever wondered what’s inside the Earth?Now let’s explore what’s inside it.

Outermost layer of the Earth.It is about 32 km. thickThe elevated portions of this layer are the continents. Underneath the continents it is about 32 kms. Thick.The lower portion forms the ocean floors. Underneath the oceans it is only about 11.2 kilometers thick.Consists mainly of a kind of rock called granite.There are atleast 90 chemical elements existing in the Crust.Only 5 of these make up most of the crust’s mass. They are oxygen, silicon, aluminum, iron, & calcium.

Zone of the earth between the MOHO discontinuity and the outer core, probably composed of dense silicate mineralsIt extends down to about 2880 kms.Te mantle is believed to be very hot. Consists of a plastic but rigid mass of material.

CORE OF THE EARTHThe central zone of

the earth about 2000 miles in diameter, and apparently composed of an iron nickel alloy.

INNER COREAbout 2880 kms. thickComposed of molten materials.

OUTER COREAbout 2800 kms thick Believed to be in liquid form

This is Bingham Canyon in Utah. It shows the real picture of the Earth upon entering severe mining industries

Sources:

http://scign.jpl.nasa.gov/learn/plate1.htmhttp://scign.jpl.nasa.gov/learn/plate.htmhttp://www.thetech.org/exhibits_events/online/quakes/inside/http://volcano.und.nodak.edu/vwdocs/vwlessons/lessons/Earths_layers/Earths_layers1.htmlhttp://www.cnn.com/interactive/nature/9903/earth.layers/frameset.exclude.html