NCERT Solutions for Class 8 Science
Chapter 17 Stars and the Solar System
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NCERT Solutions for Class 8 Science Chapter 17 Stars and the Solar System
Choose the correct answer in Questions 1-3.
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
Answer: (c) A constellation . Constellation is group of stars forming different shapes.
2. Which of the following is NOT a planet of the sun?
(a) Sirius (b) Mercury (c) Saturn (d) Earth
Answer: (a) Sirius. It is a star.
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.
Answer: (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 ____________ .
Answer: Neptune
(b) The planet which appears reddish in colour is ____________ .
Answer: Mars
(c) A group of stars that appear to form a pattern in the sky is known as a ____________ .
Answer: constellations
(d) A celestial body that revolves around a planet is known as __________.
Answer: satellite
(e) Shooting stars are actually not ____________.
Answer: stars
(f) Asteroids are found between the orbits of _________ and _________ .
Answer: mars, jupiter
5. Mark the following statements as true (T) or false (F).
(a) Pole star is a member of the solar system.
Answer: False. [ Star is not part of solar system. Solar system consist sun and celestial bodies revolving around it. ]
(b) Mercury is the smallest planet of the solar system.
Answer: True
(c) Uranus is the farthest planet in the solar system.
Answer: False. [ Neptune is farthest planet in our solar system. ]
(d) INSAT is an artificial satellite.
Answer: True
(e) There are nine planets in the solar system.
Answer: False. [ There are eight planets in our solar system. ]
(f) Constellation Orion can be seen only with a telescope.
Answer: False. [ It is visible to our naked eye. ]
6. Match items in column A with one or more items in column B.
| Column A | Column 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:
| Column A | Column 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 |
7. In which part of the sky can you find Venus if it is visible as an evening star?
Answer: Venus is called evening star and it appears in western part of the sky in evening.
8. Name the largest planet of the solar system.
Answer: Jupiter is the largest planet of solar system.
9. What is a constellation? Name any two constellations.
Answer: Constellation is group of stars forming different shapes in sky. Some constellations are orion, great bear, cassiopeia, etc.
10. Draw sketches to show the relative positions of prominent stars in – (a) Ursa Major and (b) Orion
Answer:
11. Name two objects other than planets which are members of the solar system.
Answer: Other than planets asteroids and meteors are part of solar system.
12. Explain how you can locate the Pole Star with the help of Ursa Major.
Answer: Find Ursa Major in the sky to locate pole star. Bowl of Ursa Major consist of four bright stars. Draw an imaginary straight line from two end stars towards north direction. This line meets the star, called Pole Star. Imaginary line is five time the length of two end stars of the bowl in Ursa Major.
13. Do all the stars in the sky move? Explain.
Answer: All stars in the sky move east to west except pole star. Pole star is present above the axis of rotation of the earth in north direction, therefore, it seems to be stationary in the sky.
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: Distance travelled by light in one year is called one light year. Since, distance between stars and earth and distances between stars is very large, therefore it is measured in light years. The given statement, “a star is eight light years away from the Earth” suggest that distance between star and earth is same as distance of light travelled in 8 years.
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 accomodate?
Answer: Let the radius of Earth and Jupiter be R and R’. It is provided that radius of the Jupiter is 11 times the radius of the Earth.
∴ R’ = 11 R
Consider Earth and Jupiter as two spheres.
∴ Volume of sphere with radius r can be given as ( 4/3 ) π r3
Thus, volume of Earth = (4/3)π R3
Volume of Jupiter = (4/3)π (R’)3
∴ Volume of Jupiter = (4/3)π (11 R)3 = 1331 (4/3)πR3
∴ Ratio of volume of Jupiter and Earth is,
= Volume of Jupiter / Volume of Earth
= (1331 (4/3)πR3 ) / (4/3)π R3
= 1331 / 1
The above ratio shows that 1331 Earths can be accommodated by Jupiter.
16. Boojho made the following sketch (Fig. 17.29) of the solar system. Is the sketch correct? If not, correct it.
Answer:
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Chapter 17 – Stars and the Solar System