Page 21 - Geography for Secondary Schools Student’s Book Form One

Geography for Secondary Schools
Student’s Book Form One
Exercise 2.2 12713 km

1. Explain why the orbit of the Earth
around the Sun is not a perfect circle?
2. What is the significance of the distance
of the Earth from the Sun? 12757 km
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3. What is the impact of the Earth’s
position in the Solar system on weather
elements?

Shape and size of the Earth Figure 2.3: Size and shape of the earth
However, the earth’s axis is not upright.
Activity 2.4 It is tilted relative to the plane of its orbit.

In a dimly lit room, shine a flashlight The axial tilting of the Earth refers to
towards a spherical object resting on a the angle between the earth’s rotational
flat surface like a table. Make sure the axis and a perpendicular to the plane of
flashlight is switched on and is casting its orbit around the Sun. The earth’s axis
of rotation is an imaginary line that runs
a beam of light on the spherical object. from the North Pole to the South Pole.
Observe the shadow that appears on the This tilting is approximately 23½° angle.
wall. The tilt of this axis is responsible for the
changing seasons and variations in daylight
hours throughout the year. It is significant
The Earth is the fifth largest planet in the in shaping the earth’s climate, seasons, and
solar system in terms of size and mass. Its overall environmental conditions.
shape is like a flattened sphere known as
an oblate spheroid (geoid). The flattening Activity 2.5
of the Earth is very slight as shown by the (a) Use reliable online sources to search
measurements of the North-south and East- for videos or animations of the
west distances in Figure 2.3. The distance Earth’s appearance. Study them and
through the centre from the North Pole to comment on the shape of the earth
the South Pole is approximately 12713 and its horizon.
kilometres, whereas the distance through (b) Relate your observations to the
the centre of the Earth at the Equator is evidence that support the shape of
approximately 12757 kilometres. The the Earth.
circumference of the Earth at the equator The Earth has an oblate spheroid shape.
is about 40085 kilometres while the polar There are several pieces of evidence to
circumference is 39955 (Figure 2.3). justify the spherical shape of the Earth. Such
pieces of evidences include the following:

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