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Types of galaxies - class-IX

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Constellation Orion can be seen only with a telescope. 

  1. True

  2. False


Correct Option: B
Explanation:

Orion can be also be seen during winter in the late evenings. 

Which of the following constellation contains the Pole Star?

  1. Ursa Major

  2. Ursa Minor

  3. Pleides

  4. Orion


Correct Option: B
Explanation:

Ursa Minor is located at the north celestial pole and contains the famous Little Dipper asterism, with Polaris, the North Star, located at the end of the dipper handle.

The Milky Way Galaxy has 

  1. elliptical shape

  2. spiral shape

  3. irregular shape

  4. none of these


Correct Option: B
Explanation:

Milky Way is spiral in shape.

Fill in the blank:
A vast collection of billions of stars is called a _______.
  1. universe

  2. galaxy

  3. constellation

  4. none of the above


Correct Option: B
Explanation:
Galaxy is a system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.
Earth is is Milky way galaxy.

According to best estimates today, how old is the universe ?

  1. between ten and twenty thousand years.

  2. between ten and twenty million years.

  3. between ten and twenty billion years.

  4. between ten and twenty trillion years.

  5. between ten and twenty quadrillion years.


Correct Option: C
Explanation:

The age of universe is approximately 13.82 billion years. It is the time that has passes since the Big Bang that started the building of matter, time and space itself. Time had no existence before the Big Bang.
Hence correct answer is option C.

Which of the following provides clear evidence that the universe is expanding ?

  1. the Oort cloud

  2. the Kuiper belt

  3. Saturn's ring

  4. Halley's comet

  5. the red shift of distant galaxies


Correct Option: E
Explanation:

The spectrum of light coming from galaxies have spectral lines of hydrogen ,sodium etc. We compare the spectral lines obtained from galaxy to the spectral lines obtained in laboratory of the same element .If the spectral lines of galaxy are shifted towards the red end of the spectrum (red shift) it means the galaxy is going away from earth . This implies that universe is expanding .This is one of the applications of Doppler's effect .

Community or collection of stars is called:

  1. solar system

  2. galaxy

  3. planet

  4. milky way


Correct Option: B
Explanation:

The solar system is the planetary system, where we live. It consists of the Sun and its planets, including the Earth.

A galaxy is a collection of millions of stars which are bound together to form a specific shape.
Planet is a body which revolves around a star. For eg:- The earth is a planet of the Sun which is a star.
Milky Way is the name of our galaxy. The sun and the earth are in the Milky Way.

The galaxies are usually classified on the basis of their:

  1. Mass

  2. Size

  3. Shape

  4. Any one of the above


Correct Option: C
Explanation:

Galaxies are defined on the basis of their shape.

A family of stars is called a

  1. galaxy

  2. solar system

  3. universe

  4. whirling havens


Correct Option: A
Explanation:

The family of a star is called a galaxy.

Cosmic or galactic year is :

  1. year in which a comet arrives.

  2. period taken by Earth to revolve around the Sun.

  3. year in which total solar eclipse occurs.

  4. period of Sun's revolution around galactic centre.


Correct Option: D
Explanation:

The galactic year, also known as a cosmic year, is the duration of time required for the solar system to orbit once around the center of the Milky Way galaxy. The length of one orbit range from 225 to 250 million terrestrial years.
The solar system is traveling at an average speed of 828,000 km/h or 514,000 mph within its trajectory around the galactic center, which is about one 1300th of the speed of light speed at which an object could circumnavigate the Earth's equator in 2 minutes and 54 seconds.

Fill in the blank:

Stars in a galaxy are held together by ______.

  1. light

  2. gravity

  3. radiation

  4. satellites


Correct Option: B
Explanation:
A galaxy is a large assembly of stars, gas, and dust, held together by the force of gravity.

Solar system revolves around the Milky Way galaxy with the speed of:

  1. $2.5$ $\text{light years} / s$

  2. $250\ km/s$ 

  3. $250\ \text{light years} / s$

  4. $2.5\ km/s$


Correct Option: B
Explanation:
The Solar System is travelling at an average speed of $250\ km/s$ on its trajectory around the galactic center.
The Earth belongs to Milky Way galaxy.

Milky Way is moving in local group of galaxies with a speed of:

  1. $300 \ light\  years \ {s}^{-1}$

  2. $300\  light\  years\ {hr}^{-1}$

  3. $300\ km$ ${s}^{-1}$

  4. $300m$ ${s}^{-1}$


Correct Option: C
Explanation:
$Milky \ Way$ moves through space within the cluster of galaxies it is a member of. This cluster, in turn, moves through space towards yet another larger cluster of galaxies off in the direction of the constellation $Virgo$. This speed is approximately $300 km/s.$

The total mass of all stars in Milky Way galaxy is about:

  1. $2\times {10}^{41}\ kg$

  2. $2\times {10}^{31}\ kg$

  3. $2\times {10}^{21}\ kg$ 

  4. $2\times {10}^{11}\ kg$


Correct Option: A
Explanation:
Total mass of stars in the Milky Way galaxy is about $1.9 \times 10^{41}\ kg$ 
or $=2 \times 10^{41}\ kg$.

The time taken by the Sun to revolve around the centre of our galaxy is:

  1. 25 million years

  2. 100 million years

  3. 250 million years

  4. 500 million years


Correct Option: C
Explanation:
The galactic year, also known as a cosmic year, is the duration of time required for the solar system to orbit once around the center of the Milky Way galaxy. 
1 galactic year is almost equal to 250 million years.

Fill in the blank:

If $V$ is the velocity of a receding galaxy and $R$ is the distance of the galaxy from the Earth. Then the relation between $V$ and $R$ is _______ .

  1. $V \propto \displaystyle\frac{1}{R}$

  2. $V \propto {R}^{2}$

  3. $V \propto R$

  4. $V \propto \displaystyle\frac{1}{{R}^{2}}$


Correct Option: C
Explanation:

As per Hubble Expansion Law, $H=\displaystyle \frac{V}{R}$,

where $H$ is Hubble constant. 
So, $V \propto R$.

The astronomers have estimated that the universe was formed about _____  years ago.

  1. 10 million

  2. 15 million

  3. 15 billion

  4. 50 billion


Correct Option: C
Explanation:

Age of universe is about 15 billion years

The distance between the galaxy Andromeda and Earth is ________ light years.

  1. $2 \times {10}^{6}$

  2. $3 \times {10}^{8}$

  3. $22 \times {10}^{16}$

  4. $12 \times {10}^{8}$


Correct Option: A
Explanation:

Distance between galaxy Andromeda and Earth is $2\times { 10 }^{ 6 }$

Ans : $2\times { 10 }^{ 6 }$
 

A group of stars can called as

  1. galaxy

  2. solar system

  3. universe

  4. whirling havens


Correct Option: A

The Indian name of Andromeda galaxy is

  1. Akash Ganga

  2. Milky Way

  3. Saptarishi

  4. None of these


Correct Option: D
Explanation:

Vaikunth is the name of the Andromeda galaxy. 

Ans: none of these

Galaxies are categorized on basis of their shape which includes:

  1. spiral shape galaxies

  2. elliptical galaxies

  3. irregular galaxies

  4. all of above


Correct Option: D
Explanation:

Galaxies are innumerous in the earth and are described by various shape which include irregular shape, spiral shape, eliptical shape and barred. 

Answer is $D$

Identify which of the following is not true according to the Big Bang Theory?

  1. Our universe is spreading out over time.

  2. As energy cooled down over time, particles were able to form matter.

  3. Our universe is becoming more compact over time.

  4. All energy was confined in some point from which the explosion occurred.

  5. Energy began to spread out a long time ago.


Correct Option: C
Explanation:

According to the Big Bang Theory, the universe started as energy concentrated at a single point, and spread out with time and cooled as it did to form matter from the energy that is possessed, creating lighter particles initially and forming heavier elements and molecules later. The age of the universe is around 13.82 billion years, which is the time there has been for the universe spreading.

Besides our own galaxy there are about ______ other galaxies scattered all over the universe.

  1. 2 billion

  2. 100 billion

  3. 10000 billion

  4. 1000000 billion


Correct Option: B
Explanation:
Besides our own galaxy, there are about 100 billion other galaxies scattered all over the universe.
Its a fact.

State whether true or false:

Milky Way is a family of stars, with dust and hydrogen, to which our Sun belongs.

  1. True

  2. False


Correct Option: A
Explanation:

A galaxy is vast collection of stars, dust and hydrogen gas. The solar system, our own Sun and its family or its family of planets belongs to a particular galaxy known as the Milky Way. In this way, our Sun and its family members constitute a small fraction of the galaxy.
Hence, the statement is true.

The spiral and disc shaped galaxy in which, our solar system is located is named -

  1. Milky way galaxy

  2. Andromeda galaxy

  3. Cartwheel galaxy

  4. Sunflower galaxy


Correct Option: A
Explanation:

Our solar system is a part of the Milky way galaxy which is one of the numerous galaxies in the universe. Its name "milky" is derived from its appearance as a dim glowing band arching across the night sky in which the naked eye cannot distinguish individual stars.

Fill in the blank:

Milky Way is a __________.

  1. spiral galaxy

  2. irregular galaxy

  3. elliptical galaxy

  4. quasar


Correct Option: A
Explanation:
When looked from top or bottom, Milky Way looks in spiral shape. Hence correct option is A.

State whether true or false:

Our solar system belongs to Seyfert galaxy. 

  1. True

  2. False


Correct Option: B
Explanation:
The Milky Way is the galaxy that contains our solar system.

Fill in the blank:

The billions of stars which occur in the form of groups or clusters are commonly called _______ .

  1. galaxies

  2. nebula

  3. plutons

  4. stellar


Correct Option: A
Explanation:
A system of millions or billions of stars, together with gas and dust, held together by gravitational attraction is galaxy.
The galaxy of which the solar system is a part; the Milky Way.
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