2. Motions Of The Earth
As you know that the earth has two
types of motions, namely rotation
and revolution. Rotation is the
movement of the earth on its axis.
The movement of the earth around
the sun in a fixed path or orbit is
called Revolution. The axis of the
earth which is an imaginary line,
makes an angle of 66½° with its
orbital plane.
3. Rotation of the Earth
Earth rotates once in about
24 hours with respect to
the Sun, but once every 23
hours, 56 minutes, and 4
seconds with respect to
other, distant,
stars Earth's rotation is
slowing slightly with time;
thus, a day was shorter in
the past.
4. Revolution of the Earth
A revolution or orbit is the
time it takes for the earth to
make one complete revolution
around the sun. Time for one
revolution = 365.25 days or
one year. The speed of
earth's revolution is 68,000
miles per hour. North pole
tilts towards the sun, the
Northern Hemisphere is
experiencing summer.
5. What is circle of illumination
The imaginary line that separates day
from night on earth is called the
circle of illumination.
It is basically the region that is
experiencing sunshine.
The circle of illumination cuts all
latitudes into half on the spring and
autumnal equinoxes. Another fact is
that the circle of illumination passes
through the equator in a way that it
bisects it.
