G- Give reasons:
1) The Earth is called as blue planet.
Answer- The
three-fourth of the earth's surface is covered with water bodies. And when
looked from the space it appears blue due to those water bodies. That is why it
is also known as the Blue planet.
2) We see only one side of the Moon.
Answer- The moon
takes same number of days to make a revolution and a rotation. Due to this,
only one face of moon is visible to us.
3) Life is not possible on the Moon.
Answer-Moon does
not have any water or atmosphere. Therefore, there is no life on it.
4) Earth is a unique planet.
Answer-Earth is
the only known planet where life exists. Earth has the right conditions for
supporting life. Water and air are available on earth and they are essential
for life. Earth has the right temperature for living beings. Hence, the Earth
is called a unique planet.
H- Answer the following questions in
brief:
1) What is Milky Way?
Answer-The Milky
Way is the galaxy that contains our Solar System. The Milky Way has several
satellite galaxies and is part of the Local Group of galaxies, which form part
of the Virgo Super cluster, which is itself a component of the Laniakea
Super cluster.
2) What is a constellation? Give an example?
Answer- In the
night sky, you can see different patterns formed by groups of stars. Such a
pattern of stars is called constellation. Examples are Saptarishi Mandal [Ursa
Major (Great Bear)], Orion, Leo, Gemini.
3) What is the importance of the Sun in our
Solar System?
Answer-The system
formed by the Sun, eight planets, satellites, asteroids and various other
celestial bodies is called the Solar System. The sun is at the centre & the
head of the solar system. It controls the movement of the bodies by its
gravitational pull.
4) What is a celestial body?
Answer-The Sun,
the Moon, planets, stars and other bodies in the Universe are called celestial
bodies.
5) Why Venus is the hottest planet in the
Solar System?
Answer- Venus is
the hottest planet in the Solar System due to the green house effect in its
atmosphere.
6) What are satellites?
Answer- Some
celestial bodies keep on moving around a planet. They are called satellites.
I-Answer the following questions in
detail:
1) What do you understand by stars?
Answer- Some
celestial bodies are very big and hot. They are made up of gases. They have
their own heat and light. A celestial body which emits its own heat and light
is called a star.
2) What is the Solar System made of?
Answer- The
system formed by the Sun, eight planets, satellites, asteroids and various
other celestial bodies is called the Solar System. The Sun is at the centre of
the solar system.
3) Why the Earth is called a unique planet?
Answer: Earth is
the only known planet where life exists. Earth has the right conditions for
supporting life. Water and air are available on earth and they are essential
for life. Earth has the right temperature for living beings. Hence, the Earth
is called a unique planet.
4) What are asteroids and where are they
found?
Answer- There is
numerous small bodies which move around the Sun. These are present between the
orbits of Jupiter and Mars. These are called asteroids.
5) What are phases of Moon?
Answer- New Moon - The first phase of
the moon. In this phase, the moon is completely dark since we can’t see the
side that the sun is shining on.
Crescent Moon- The
second phase of the moon. In this phase, we can see sunlight reflecting off
only about one quarter of the moon’s surface that faces us.
Quarter Moon- The
third phase of the moon. In this phase, we can see sunlight reflecting off half
of the moon’s surface that faces us.
Gibbous Moon- The
fourth phase of the moon. In this phase, we can see sunlight reflecting off
three quarters of the moon’s surface that faces us. It’s not a full moon yet,
but it’s getting there.
Full Moon- The
fifth phase of the moon. In this phase, we can see sunlight reflecting off all
of the moon’s surface that faces us. In this phase the moon appears round and
completely lit up.
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