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6.2 Form of the Earth

6.2.2 Describe the general shape of the earth.

The Earth is not a perfect sphere.

It is flatter at both the poles as if something was squeezing the earth, so it is actually an Oblate Spheroid.

But for practical purposes, we can assume the earth to be a proper Sphere.

6.2.4 Define and identify, on a diagram of the earth: 

(a) axis and direction of rotation; 

Looking down at the earth onto the North Pole, it can be seen to spin around its polar axis in an anti-clockwise direction.

The polar axis passes through two points, the North geographic pole and the South geographic pole, known respectively as True North and True South.

(b) geographic and magnetic poles; 

The earth is essentially a large magnet with a field of magnetic force, or flux, around it.

A freely suspended compass needle will align itself with the flux lines and under most conditions a stable direction reference is provided with reference to the magnetic poles.

The geographic and magnetic poles are not situated in the same place.

They are about 1000 miles away from each other.

The North and South geographic poles are fixed locations which the earth rotates about while the magnetic poles will move in a full circle around the geographic poles roughly every 900 years.

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