Class 8 - Physics - Stars and the Solar System

Question1.

Choose the correct answer in Question:

Which of the following is NOT a member of the solar system?

(a) An asteroid

(b) A satellite

(c) A constellation

(d) A comet

Answer:

Correct option is (c) A Constellation.  It is not a member of the solar system as constellations are the stars forming a recognisable shape.

Question2.

Choose the correct answer in Question:

Which of the following is NOT a planet of the sun?

(a) Sirius

(b) Mercury

(c) Saturn

(d) Earth

Answer:

Correct option (a) Sirius. It is not a planet but a star.

Question 3.

Choose the correct answer in Question:

Phases of the moon occur because

(a) we can see only that part of the moon which reflects light towards us.

(b) our distance from the moon keeps changing.

(c) the shadow of the Earth covers only a part of moon’s surface.

(d) the thickness of the moon’s atmosphere is not constant.

Answer:

Phases of the moon occur because (a) we can see only that part of the moon which reflects light towards us.

Question 4.

(a) The planet which is farthest from the Sun is ____________.

(b) The planet which appears reddish in colour is ____________.

(c) A group of stars that appear to form a pattern in the sky is known as a ____________.

(d) A celestial body that revolves around a planet is known as __________.

(e) Shooting stars are actually not ____________.

(f) Asteroids are found between the orbits of _________ and _________.

Answer:

(a) The planet which is farthest from the Sun is Neptune.

(b) The planet which appears reddish in colour is Mars.

(c) A group of stars that appear to form a pattern in the sky is known as a Constellation.

(d) A celestial body that revolves around a planet is known as Satellite.

(e) Shooting stars are actually not Stars.

(f) Asteroids are found between the orbits of Mars and Jupiter.

Question 5.

Mark the following statements as true (T) or false (F):

(a) Pole Star is a member of the solar system. ( )

(b) Mercury is the smallest planet of the solar system. ( )

(c) Uranus is the farthest planet in the solar system. ( )

(d) INSAT is an artificial satellite. ( )

(e) There are nine planets in the solar system. ( )

(f) Constellation Orion can be seen only with a telescope. ( )

Answer:

(a) Pole Star is a member of the solar system. (F)

(b) Mercury is the smallest planet of the solar system. (T)

(c)  Uranus is the farthest planet in the solar system. (F)

(d) INSAT is an artificial satellite. (T)

(e)  There are nine planets in the solar system. (F)

(f)  Constellation Orion can be seen only with a telescope. (F)

 Question 6.

Match items in column A with one or more items in column B:

A                                             B

(i) Inner planets                 (a) Saturn

(ii) Outer planets               (b) Pole Star

(iii) Constellation               (c) Great Bear

(iv) Satellite of the Earth    (d) Moon

                                       (e) Earth

                                        (f) Orion

                                        (g) Mars

 Answer:

      A                                           B

(i) Inner planets              (e) Earth, (g) Mars

(ii) Outer planets               (a) Saturn

(iii) Constellation               (c) Great Bear, (f) Orion

(iv) Satellite of the Earth     (d) Moon

 Question 7.

In which part of the sky can you find Venus if it is visible as an evening star?

Answer:

Venus appears in the western sky after sunset that is why it is called as evening star.

Physics Class 8 Stars Venus

Question 8.

Name the largest planet of the solar system.

Answer:

Jupiter is the largest planet of the solar system. It is so large that about 1300 earths can be placed inside this giant planet.

However, the mass of Jupiter is about 318 times that of our Earth. It rotates very rapidly on its axis.

Physics Class 8 Jupiter

Question 9.

What is a constellation? Name any two constellations.

Answer:

The star forming a group that has a recognisable shape is called a constellation. Example: - Great Bear, Orion, Leo Major etc.

Physics Class 8 Constellation

Question 10.

Draw sketches to show the relative positions of prominent stars in

(a) Ursa Major and (b) Orion

Answer:

Ursa Major: - There are seven prominent stars in this constellation. It appears like a big ladle or a question mark.

Physics Class 8 Stars Ursa Major

There are three stars in the handle of the ladle and four in its bowl as shown in the figure.

  • Orion: - It is one of the most magnificent constellations in the sky. It also has seven or eight bright stars [Fig] Orion is also called the Hunter.
  • The three middle stars represent the belt of the hunter.

The four bright stars appear to be arranged in the form of a quadrilateral.

 Physics Class 8 Star Orion

Question 11.

Name two objects other than planets which are members of the solar system?

Answer:

Asteroids and Meteors are objects other than planets which are members of the solar system.

Physics Class 8 Stars Objects

Question 12.

Explain how you can locate the Pole Star with the help of Ursa Major.

Answer:

The pole star can be located by using Ursa Major constellation. We can look for 2 stars at the end of Ursa Major.

Imagine a straight line passing through these stars as shown in the Fig. Extend this imaginary line towards the north direction.

This line will lead to a star which is not too bright. This is the Pole Star.

Physics Class 8 Locating Pole Star

Question 13.

Do all the stars in the sky move? Explain.

Answer:

No, the earth rotates on its axis from west to east. Therefore, all the stars in the sky (except the pole star)

seem to move from east to west. With reference to Earth, pole star in the sky does not seem to move

because it is located above the axis of rotation of the Earth in the north direction. It seems to remain stationary at a point in the sky.

Physics Class 8 Pole Star

Question 14.

Why is the distance between stars expressed in light years? What do you understand by the statement that a star is eight light years away from the Earth?

Physics Class 8 Solar System

Answer:

The distance between the stars and earth is millions of kilometres, are very far from the earth. The large distances are expressed in light years.

1 light year = 9.46 x 1012 km

A star is located eight light years away from the Earth.

This means that the distance between the star and the Earth is equivalent to the distance travelled by light in eight years.

So the distance between the earth and star = 8x (9.46 x 1012) =7.6 x 1013 km.

 Physics Class 8 Stars Solar System

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