Page 98 - SST Class 06

Exploring Our

Solar System 15

q About universe q Celestial bodies and constellations
q About the Solar System q Relation between the Sun and other planets
q Heavenly bodies (asteroids, meteorites, comets)

Introduction travels in one year makes a light year. Just imagine
how long it is!
When we look at the sky during the day we see the
bright sun, but at night the sky looks very beautiful Galaxy
with the Moon and million of stars. There are many There are many galaxies
other objects in the sky like planets, comets,
in the universe. A galaxy
meteors, meteorites, asteroids etc. All these objects
has millions of stars and
are called heavenly bodies or celestial bodies . All other bodies. Our Earth is
these celestial bodies are part of the universe. a part of a galaxy called

the Milky Way or Akash
UNIVERSE Ganga . This galaxy is so

Universe is everything we can touch, feel, sense, big that it contains about
measure or detect. It includes living things, one million million stars. Galaxy
planets, stars, galaxies, dust clouds, light and even If we look at the sky in a dark night, we can see a
time. It is believed that the universe came into faint band of light which stretches across the sky.
being as a result of the Big Bang and continues to This is the Milky Way in which we are situated.
get bigger. The universe is incredibly huge. It
would take a modern jet fighter more than a Constellations
million years to reach the nearest star to the Sun. Look at the sky at night. You will find that most
stars are shining single, while some appear to be
Info Bits
Info Bits in some sort of group or pattern. A group of stars
is called a constellation . In the ancient times,
The branch of science that deals with the study of these constellations were attributed some
stars, planets and other heavenly bodies is called imaginary shapes and it was believed that they
astronomy. influenced the life of man.

Measuring Distances in the Space
The celestial bodies are located at huge distances
from one another. These distances are so vast that
they cannot be measured using the ordinary units
of length, like kilometres or miles. In view of this,
the astronomers use light year as the unit of
distance in the space. Light travels about 3,00,000
km in one second. So, the distance that light
Saptarishi
Contemporary Social Science-6
98