Planets of Our Solar System

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Earth

Slide 18

The earth rotates on its axis.It rotates on an imaginary axis which phases which through its north and south pole. The average temperature of the surface of the earth is 15°c The earth has one natural satellite called moon. The two major factors which factors which are responsible for the existence of life on the planet earth are :size of the earth and distance of the earth from the sun.

Slide 19

The motions of the earth

Rotation

The earth rotates or spin on an imaginary axis which phases through its north and south poles.The earth completes one rotation on its axis in 24 hours which we call one day. This causes day and night.The earth rotates on its axis from east to west.The axis of rotation of earth is slightly tilted with respect to the plane of its orbit around the sun.

Slide 20

The rotation of the earth causes Day and Night.

An important consequence of the rotation of the earth on its axis is that it causes day and night on the earth. As the earth rotates on its axis, first one half of the Earth is turned around towards the sun. This part of earth receives sunlight and has day on it. The part of earth which is turned away from the sun does not receive any sunlight, it remains dark and has night.Almost every 12 hours, a day changes into night, and a night changes into day.The change in the length of a day and night is, however, caused by the tilt of Earth’s axis.

Slide 21

Slide 22

Satellite of the Earth:Moon

Slide 23

The Motion of the Earth Around the Sun Causes Seasons

An important consequence of the revolution of the Earth around the sun is that it causes seasons on the earth such as summer, winter, spring and autumn. Two factors are responsible for causing different seasons on the Earth.These are:

1. Motions of the earth around the sun once every year.

2. Tilt of the Earth’s axis to the plane of its orbit around the sun.

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Slide 25

In The Northern hemisphere:

1)It is winter when the earth is closer to the sun.

2)It is summer when the earth is farther from the sun.

In the Southern hemisphere: 1)It is summer when the earth is closer to the sun.

2)It is winter when the earth is farther from the sun.