(Geography for civil service exams, APPSC Material, APPSC Notification, Bankpo & IBPS Exam) AXIS AND ITS INCLINATION: The earth's axis is an imaginary line that passes through
its centre. Its two ends are the North Pole and the South Pole. This axis is inclined to the plane of the earth's
orbit at an angle of 6672°.
Besides
moving round the sun, our earth also moves on its own axis. Thus, our earth has
two kinds of motions — one on its axis, which we call 'Rotation' and the other
around the sun, which we call 'Revolution'.
ROTATION:
The
movement of the earth round its axis in 24 hours is called Rotation. Because of
rotation the days and nights are caused.
Day
and Night and Circle of Illumination: It is because of the earth's rotation that the sun seems to
us rising and setting. When the earth moves on its axis, half of its surface
faces the sun at a time while the other half remains away from the sun. That
part of the earth which receives sunlight is called the circle of illumination.
As a
result, in that part of the earth that receives illumination or sunlight, it is
the day while in the other part it is the night. This phenomenon of alternating
day and night is the result of the earth's movement on its axis, which we call 'Rotation' and which it completes in 24
hours or in one day.
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