Page 12 - sst_class_06

Chapter 2 motion of the earth

In ancient time, people believed that the earth was stationary
and other heavenly bodies like the sun, moon moved around it.

In the 16th century, Nicolaus Copernicus, a polish astronomer
was the first to say that the earth is moving on its axis and also
moving around the sun.

Movement of Earth on its axis
earth’S motion

The earth exhibits two different kinds of motion. One is rotation around its own axis and
another movement is revolution, it revolves around the sun in a fixed orbit.

1. rotation of the earth

The earth rotates on its axis from west to east. The axis of the earth is an imaginary line which
passes through its centre from the North Pole to the South Pole. The axis of the earth is not
vertical, it is inclined at an angle of 66 ½° to the plane of the earth’s orbit.
The earth takes 24 hours to complete one rotation. Rotation of the earth causes day and night.
The surface of the earth that is facing the sun gets the light and called day.

The surface of the earth that is opposite to the face of the sun does not get light and called night.

exPeriment

Take a globe and a torch. Keep the globe in a dark
room and light the torch. The part of the globe
which faces the torch gets light and other half
does not have light. Similarly, one half of the earth

gets light and other half does not get light.

Places near the equator have almost equal days
and night throughout the year. As we move towards At the poles, there are six months of day
the poles, the length of day and night changes and six months of night.

depending upon the seasons.
2. revolution of the earth

The movement of the earth around the sun in a fixed path or orbit is called Revolution. The
earth goes around the sun in an elliptical orbit. The earth takes 365 ¼ days to complete one
revolution. One year has 365 days, but after every 4 years, one extra day is added to the

12 Social Studies-6