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NCERT Solutions for Class 8th Science Chapter 17 : Stars and the Solar System

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CBSE NCERT Solutions for Class 8th Science Chapter 17 : Stars and the Solar System . NCERT Class 8 Science Solutions for Chapter 17. Class VIII Science Solutions NCERT


NCERT Solutions for Class 8th Science Chapter 17 : Stars and the Solar System

 

Page No: 234

Excercise

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
► (c) A constellation

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

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

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 a_________.
(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 asatellite.
(e) Shooting stars are actually not stars.
(f) Asteroids are found between the orbits of Mars and Jupiter.

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5. Mark the following statement as true (T) or false (F).

(a) Pole star is a member of the solar system. ( )
► False

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

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

(d) INSAT is an artificial satellite. ( )
► True

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

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

► False

Page No: 235

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 (g), (e) Mars, Earth
(ii) Outer planets (a) Saturn
(iii) Constellation (c), (f) Great Bear, Orion
(iv) Satellite of the Earth (d) Moon

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 and is called the evening star.
8. Name the largest planet of the solar system.
► Jupiter

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

Answer

A constellation is a group of stars that form a recognisable pattern in the sky.
The two constellations name are Ursa Major and Orion.

10. Draw sketches to show the relative position of prominent stars in (a) Ursa Major and (b) Orion.

Answer

(a) Ursa Major appears like a big dipper. There are three bright stars in the handle and four stars in the bowl of the dipper as shown in below figure.

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Ursa Major

(b) Orion appears like a hunter. Three bright stars appear in the belt, while five bright stars are arranged in the form of a quadrilateral as shown in the below figure.

Ursa Minor

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.

Page No: 237

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

Answer

The pole star can be located using the ursa major constellation, by imagining a line towards the Northern direction connecting two stars presnt at the end of the bowl, This imaginary line meets Pole Star. The length of the imaginary line from the bowl is about five times the distance between the two stars of the bowl.

Location of Pole star witht he help of Ursa Major

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

Answer

No, Stars do not move they actually appear to move from east to west due to rotation of earth on its axis from west to east.

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?

Answer

The distance of the stars from the Earth and the distance between the stars are very large. It is inconvenient to express these distances in kilometer (km). Thus, 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 1012km.
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 1013km away from the Earth.

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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?

Answer

Earth and Jupiter can be considered as two spheres with radii Rand R’ respectively. Given that the radius of Jupiter is 11 times the radius of the Earth.
Thus, R’ = 11 R

http://2.bp.blogspot.com/-PSna60uhYP0/VPKUot903WI/AAAAAAAAEL4/yaZ8vNGWK0I/s1600/equation-class-8th-chapter-17.PNG
16. Boojho made the following sketch (Fig. 17.29) of the solar system. Is the sketch correct? If not, correct it.

http://4.bp.blogspot.com/-ejcRt0NAOr4/VPKVZW8NIDI/AAAAAAAAEMA/qC3xLaHKcAQ/s1600/fig-17.29-class-8th-question-chapter-17.PNG

Answer

No, the sketch is not correct as the planet because he has interchanged the positions of Mars and Venus and also the positions of Uranus and Neptune. Also, he has shown the Asteroid belt in the gap between the orbits of Jupiter and Saturn which is not correct. The asteroid belt is located between the orbits of Mars and Jupiter. The correct fig is given below.

http://4.bp.blogspot.com/-9_9PI_yXejs/VPKWl_SRShI/AAAAAAAAEMM/eo2yUr4mfrA/s1600/fig-17.29-class-8th-answer-chapter-17.PNG


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