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• The Solar System is also home to two regions populated
by smaller objects. The asteroid belt, which lies between
Mars and Jupiter, is similar to the terrestrial planets as it
is composed mainly of rock and metal. Beyond Neptune's
orbit lie trans-Neptunian objects composed mostly of
ices such as water, ammonia and methane. Within these
two regions, five individual objects, Ceres, Pluto,
Haumea, Makemake and Eris, are recognized to be large
enough to have been rounded by their own gravity, and
are thus termed dwarf planets. In addition to thousands
of small bodies in those two regions, various other small
body populations, such as comets, centaurs and
interplanetary dust, freely travel between regions.
The Solar System is also home to two regions populated
by smaller objects. The asteroid belt, which lies between
Mars and Jupiter, is similar to the terrestrial planets as it
is composed mainly of rock and metal. Beyond
Neptune's orbit lie trans-Neptunian objects composed
mostly of ices such as water, ammonia and methane.
Within these two regions, five individual objects, Ceres,
Pluto, Haumea, Makemake and Eris, are recognized to be
large enough to have been rounded by their own gravity,
and are thus termed dwarf planets. In addition to
thousands of small bodies in those two regions, various
other small body populations, such as comets, centaurs
and interplanetary dust, freely travel between regions.
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The solar wind, a flow of plasma from the Sun, creates a
bubble in the interstellar medium known as the
heliosphere, which extends out to the edge of the
scattered disc. The hypothetical Oort cloud, which acts
as the source for long-period comets, may also exist at a
distance roughly a thousand times further than the
heliosphere.
Six of the planets and three of the dwarf planets are
orbited by natural satellites, usually termed "moons"
after Earth's Moon. Each of the outer planets is
encircled by planetary rings of dust and other particles.
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THE SUN, THE MOON AND ALL THOSE
OBJECTS SHINING IN THE NIGHT SKY
ARE CALLED ‘CELESTIAL BODIES’
SOME CELESTIAL BODIES ARE VERY
BIG AND HOT. THEY ARE MADE UP OF
GASES. THEY HAVE THEIR OWN HEAT
OR LIGHT, WHICH THEY EMIT IN
LARGE AMOUNTS. THESE CELESTIAL
BODIES ARE CALLED ‘STARS’
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SOME CELESTIAL BODIES
ARE VERY BIG AND HOT.
THEY ARE MADE UP OF
GASES. THEY HAVE THEIR
OWN HEAT OR LIGHT,
WHICH THEY EMIT IN
LARGE AMOUNTS. THESE
CELESTIAL BODIES ARE
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The Solar System
THE SUN, NINE PLANETS,
SATELLITES AND SOME
OTHER CELESTIAL BODIES
KNOWN AS ASTEROIDS AND
METEOROIDS FORM THE
SOLAR SYSTEM. WE OFTEN
CALL IT A SOLAR FAMILY,
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The Sun
The Sun is in the centre of the Solar
System. It is huge and made up of
extremely hot gases. It provides the
pulling force that binds the Solar System.
The Sun is the ultimate source of heat and
light for the Solar System. But the
tremendous heat is not felt so much by us
because despite being our nearest star, it is
far away form us. The Sun is about 150
million km away for the earth.
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The Solar System consists of the Sun and the astronomical
objects bound to it by gravity, all of which formed from the
collapse of a giant molecular cloud approximately 4.6 billion
years ago. Of the many objects that orbit the Sun, most of the
mass is contained within eight relatively solitary planets whose
orbits are almost circular and lie within a nearly flat disc called
the ecliptic plane. The four smaller inner planets, Mercury,
Venus, Earth and Mars, also called the terrestrial planets, are
primarily composed of rock and metal. The four outer planets,
the gas giants, are substantially more massive than the
terrestrials. The two largest, Jupiter and Saturn, are composed
mainly of hydrogen and helium; the two outermost planets,
Uranus and Neptune, are composed largely of ices, such as
water, ammonia and methane, and are often referred to
separately as "ice giants".
Planets
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The Earth is the third nearest planet to the Sun. In size, it
the fifth largest planet. It is slightly flattened at the poles.
That is why, its shape is described as a Geoid. Geoid
means an Earth-like shape.
Conditions favourable to support life are probably found
only on earth. The Earth is neither too hot nor too cold.
It has water and air, which are very essential for our
survival. The air has life supporting gases like oxygen.
Because of these reasons the Earth is a unique planet in
the Solar System.
From the outer space, the earth appears blue because its
two thirds surface is covered by water. It is, therefore
called a Blue Planet.
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The Moon
Our Earth has only one satellite that is the Moon. Its
diameter is only one-quarter that of the earth. It
appears so big because it is nearer to our planet than
other celestial bodies. It is about 3,84,400 km away
form us.
The Moon moves around the Earth in about 27 days. It
takes exactly the same time to complete one spin. As a
result only one side of the moon is visible to us on the
Earth.
The Moon does not have conditions favourable for life.
it has neither water nor air. It has mountains plains and
depressions on its surface. These cast shadows on the
Moon’s surface.
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Asteroids
Apart from the stars , planets and satellites,
there are numerous tiny bodies which also
move around the sun. These bodies are
called Asteroids.
They are found between the orbits of Mars
and Jupiter. The largest asteroid is the Ceres.
Scientists are of the view that asteroids are
parts of a planet which exploded many years
back.
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Meteoroids
The small pieces of rocks which move
around the sun are called Meteoroids.
Sometimes these meteoroids come
near the earth and tend to drop upon it.
During this process due to friction
with the air they get heated up and
burn. It causes a flash of light.
Sometimes, a meteor without being
completely burnt, falls on the earth
and creates a hollow.
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Jupiter
Galaxy
Do you see a whitish broad band, like a
white glowing path across the sky on a clear
starry night?
It is cluster of million of stars . This band is
the Milky Way Galaxy.
In ancient India, it was imagined to be a
river of light flowing in the sky. Thus, it
was named Akash Ganga.