NCERT Solutions for Class 8 Science Chapter 17 Stars And The Solar System

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Updated at 2021-03-31


NCERT solutions for class 8 Science Chapter 17 Stars And The Solar System Exercise

Q.1 Which of the following is NOT a member of the solar system?
(a) An asteroid
(b) A satellite
(c) A constellation
(d) A comet



NCERT Solutions for Class 8 Science Chapter 17 Stars And The Solar System


Answer :

(c) A constellation

A constellation is an area on the celestial sphere in which a group of visible stars forms a perceived outline or pattern.

Q.2 Which of the following is NOT a planet of the sun?
(a) Sirius
(b) Mercury
(c) Saturn
(d) Earth



NCERT Solutions for Class 8 Science Chapter 17 Stars And The Solar System


Answer :

(a) Sirius

Sirius is the brightest star in the night sky.

Q.3 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 the moon’s surface.
(d) the thickness of the moon’s atmosphere is not constant.



NCERT Solutions for Class 8 Science Chapter 17 Stars And The Solar System


Answer :

Phases of the moon occur because

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

Q.4 Fill in the blanks.
(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 _________ .



NCERT Solutions for Class 8 Science Chapter 17 Stars And The Solar System


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.

Q.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.



NCERT Solutions for Class 8 Science Chapter 17 Stars And The Solar System


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 )

Q.6 Match items in column A with one or more items in column B.

Column A
(i) Inner planets
(ii) Outer planets
(iii) Constellation
(iv) Satellite of the Earth
Column B
(a) Saturn
(b) Pole star
(c) Great Bear
(d) Moon
(e) Earth
(f) Orion
(g) Mars



NCERT Solutions for Class 8 Science Chapter 17 Stars And The Solar System


Answer :

Column A

(i) Inner planets
(ii) Outer planets
(iii) Constellation
(iv) Satellite of the Earth

Column B

(g) Mars (e) Earth
(a) Saturn
(c) Great Bear (f)Orion
(d) Moon

Q.7 In which part of the sky can you find Venus if it is visible as an evening star?



NCERT Solutions for Class 8 Science Chapter 17 Stars And The Solar System


Answer :

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

It is the second planet from the Sun.

It is hotter than Mercury despite being farther away from the Sun.

Q.8 Name the largest planet of the solar system.



NCERT Solutions for Class 8 Science Chapter 17 Stars And The Solar System


Answer :

Jupiter is the largest planet of the solar system.

It is the fifth planet from the Sun.

It is known for its stripes and large red spot.

Q.9 What is a constellation? Name any two constellations.



NCERT Solutions for Class 8 Science Chapter 17 Stars And The Solar System


Answer :

A constellation is an area on the celestial sphere in which a group of visible stars forms a perceived outline or pattern. Those group of stars form a recognizable shape.

Example: Ursa Major, Orion

Q.10 Draw sketches to show the relative positions of prominent stars in
(i) Ursa Major and
(ii) Orion



NCERT Solutions for Class 8 Science Chapter 17 Stars And The Solar System


Answer :

Q.11 Name two objects other than planets which are members of the solar system.



NCERT Solutions for Class 8 Science Chapter 17 Stars And The Solar System


Answer :

Two objects other than planets which are members of the solar system are:-

Comets and Asteroids

EXPLANATION

Comets are frozen leftovers which are formed from the dust, rock and ices that are present in the solar system.

Asteroids are rocky worlds revolving around the sun that and are too small to be called as planets. They are also known as planetoids or minor planets.

Q.12 Explain how you can locate the Pole star with the help of Ursa Major.



NCERT Solutions for Class 8 Science Chapter 17 Stars And The Solar System


Answer :

In order to locate the Pole star in the sky, first the Ursa Major Constellation must be located. Then locate a quadrilateral consisting of four bright stars as shown in the given figure.



Consider two stars at the end of Ursa Major Constellation. Now, draw an imaginary straight line in the north direction connecting these two stars (as shown in the given figure).



This imaginary line meets a star called as the Pole Star.

Q.13 Do all the stars in the sky move? Explain.



NCERT Solutions for Class 8 Science Chapter 17 Stars And The Solar System


Answer :

No all the stars in the sky doesn't move.

The Earth rotates from West to East on its own axis. Hence, all stars in the sky (except the Pole star) appear to move from East to West.

With reference to the Earth, the Pole star does not appear to move in the sky because it is located above the axis of rotation of the Earth i.e., in the north direction. Thus it appears to remain stationary at a point in the sky.

Q.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?



NCERT Solutions for Class 8 Science Chapter 17 Stars And The Solar System


Answer :

The distance of the stars from the Earth and the distance between different stars are very large. It is inconvenient to express these distances in kilometer(km). Hence these large distances are expressed in light years.

One light year is the distance travelled by light in one year.
One light year is equal to 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, i.e., a star is located 8 x (9.46 x 1012) = 7.6 x 1013 km away from the Earth.

Q.15 The radius of Jupiter is 11 times the radius of the Earth. Calculate the ratio of the volumes of Jupiter and the Earth. How many Earths can Jupiter accommodate?



NCERT Solutions for Class 8 Science Chapter 17 Stars And The Solar System


Answer :

Let us consider Jupiter and Earth are two spheres with radii R and R' respectively.
Given in the question is that the radius of Jupiter is 11 times the radius of the Earth.

Radius of Earth = 11 x Radius of Jupiter
This implies, R’= 11 x R

As we know that volume of sphere of radius r is given as = (4/3) x (22/7) x r3

Volume of Earth = (4/3) x (22/7) x (R')3 = (4/3) x (22/7) x (11 x R )3

Volume of Jupiter = (4/3) x (22/7) x (R)3

The ratio of the volume of Jupiter to the volume of Earth is as follows:

Volume of Jupiter / Volume of Earth

= (4/3) x (22/7) x (R)3 / (4/3) x (22/7) x (11 x R )3

= 1 / 1331

Therefore, this ratio suggests that Jupiter can accommodate 1331 numbers of Earth in it.

Q.16 Boojho made the following sketch (Fig. 17.29) of the solar system. Is the sketch correct? If not, correct it.



NCERT Solutions for Class 8 Science Chapter 17 Stars And The Solar System


Answer :

No, the sketch made by Boojho is not correct.
The correct sketch is given below :



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