The Planets
Planets are large masses of matter that orbit around
a star. Our solar system consists of eight planets –
Mercury, Venus, Earth, Mars, which are called inner or
rocky planets, and Jupiter, Saturn, Uranus and Neptune,
which are the outer planets, or gas giants.
Quick Q’s:
1. How did the planets
get their names?
All the planets are
named after Roman
gods. Venus is named
after the Roman
goddess of love. The
surface features of
Venus are also named
after various goddesses.
For example the planet
has a deep canyon
named Diana, after
the Roman goddess
of hunting.
2. How many rings
do Jupiter and
Uranus have?
Jupiter has three thin
rings that cannot be
seen even with the
most powerful
telescopes. Uranus
has as many as
11 rings.
3. How many moons
does Venus have?
Apart from Mercury,
Venus is the only other
planet in the solar
system that has no
moon.
4. What about Pluto?
Until recently, Pluto
was the ninth planet
in our solar system.
But in 2006, it was
officially reclassified as
a dwarf planet, because
it is so small and its
gravitational field is
not as strong as that of
the major planets.
Q How were the planets formed?
A After the gaseous cloud called the
solar nebula collapsed upon itself due to
the strength of its own gravity and formed
the Sun, the dust and particles around it
clumped together to form the planets.
The heat of the Sun melted the ice particles
nearby and eventually these rocks grew larger
to form the four rocky planets. Some ice
particles were too far away from the Sun to be
melted. These ice pieces combined with gases
to form the planets called the gas giants.
Q What are the features of a rocky planet?
A The rocky planets are made up of rocks
and metals like iron and nickel. They are
smaller than the gas giants but are very heavy.
It is because of their weight that rocky planets
rotate much slower than the gas giants.
Q What makes gas giants unique?
A The gas giants are bigger in size but
lighter, as they are mainly made up of gases
and ice particles. In fact, Saturn is so light
that it would float if placed in water! Gas
giants also spin extremely quickly and they
have rings around them. These planets do
not have a hard surface. Jupiter and Saturn
have a semi-liquid centre that is covered by a
layer of liquid gas.
Birth of planets
The planets in our solar system were born when dust
and particles around the Sun clumped together.
Gas giants
The four outer planets, the gas giants, are much larger
than the Earth.
Rocky planets
Among the rocky planets, the Earth appears blue from
outer space because over 70 per cent of its surface is
covered with water.
Earth
Jupiter
Saturn
Uranus
Neptune
Earth
Mercury
Venus
Mars
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