6.2 Form of the Earth

6.2.2 Describe the general shape of the earth.

• The Earth is not a perfect sphere but a spheroid.

• It is slightly flattened at the poles.

• Due to its rotation on its axis between the North and South Poles, it is classified as an oblate spheroid.

• For most practical purposes, the Earth is regarded as a perfect sphere.

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

(a) Axis and Direction of Rotation; 

• The Earth rotates on an imaginary axis that passes through the North and South Poles.

• The poles are fixed points at the ends of this axis.

• They are known as the North and South Geographic Poles, also called True North and True South.

• When viewed from the side along the equatorial plane, the Earth rotates from west to east.

• Viewed from above the North Pole, the Earth turns in an anticlockwise direction.

(b) Geographic and Magnetic Poles; 

• The magnetic pole is the point where the Earth’s magnetic field passes vertically into the planet.

• The geographic and magnetic poles are not located in the same position.

• The North Magnetic Pole is currently about 400 km south of the North Geographic Pole, but it can shift to as much as 1,000 km away.