Page 100 - SST Class 06

planet. There are two types of satellites—natural
Activity
Prepare a model of the Solar System. Use thermocol
sheet for the base and ball of different sizes and
colours to show the planets and other bodies.
OUR PLANET : THE EARTH
The Earth is the third nearest planet to the Sun and
fifth largest of all planets in the Solar System. It is a
unique planet because this is the only planet
known to have life.
The uniqueness of the Earth
lies in the fact that it receives
the just right amount of
sunlight which can support
life. Also, it has the presence
of air and water, which are
necessary for life. Earth
The Earth revolves round the Sun once in a year
and it takes a day to rotate on its axis. The Earth is
not a true sphere, it is a bit pear-shaped, bulging at
the Equator and is flattened at the Poles. Its
equatorial diameter is about 44 km more than the
polar diameter.
If you look at the Earth from the outer space, it
appears blue. This is due to a large amount of
water on its surface. You know that about three-
fourth of its surface is covered with water, so it
appears to be blue. Due to this, it is also called the
Blue Planet or the Watery Planet.
Just Think!
Why do not we move when earth rotates?
Info Bits
Info Bits
q The Earth is the only planet in the Solar System
which is not named after a mytho logical deity.
All other planets are so named.
q The hottest planet is the Venus though Mercury
is closest to the Sun.
q The Neptune takes 165 years to go round the
Sun once.
The Satellites
A satellite is a body which revolves round a
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and man-made. The Moon is a natural satellite of
the Earth. The Uranus and Neptune have 18
natural satellites each. The man-made satellites are
launched by us in the space, like the INSAT-1
satellite.
The Moon
The Moon is the natural satellite of the Earth. It
has no light of its own, it only reflects the light of
the Sun. Its reflected light reaches the Earth in
about one and a quarter seconds, because it is
located 3,84,000 km from us.
Phases of the Moon : The Moon revolves round
the Earth and rotates on its axis in exactly the
same time, that is, 27.3 days. It means that we
always see the same side of the Moon. The part of
the Moon which we can see is the part which is in
sunlight.
Due to these phases, we can see the changing
shape of the Moon. When its shape appears to
change from New Moon (moonless night or
Amavasya) to Full Moon (or Poornima), it is said
to wax . And when its shape appears to decrease
from Full Moon to New Moon, it is said to wane .
We cannot see the Moon on the New Moon night.
Half Moon
Gibbous Crescent Moon
Moon
Full Moon New Moon
Gibbous Waning Moon
Moon Third Quarter
Phases of Moon
Info Bits
Info Bits
Neil Armstrong and Edwin Aldrin, the American
astronauts, were the first to set foot on the Moon
in 1969.