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

This is an interesting chapter. Students will explore our solar system and learn about the other planets in it. They will also become familiar with terms like constellations, comets, asteroids, satellites etc.

We see stars in the night sky. We can also see the moon and constellations as well as shooting stars. Students will find it interesting to learn about what shooting stars are and how they occur.

✍ Download PDF of Class 8 Science Chapter 17 Solutions

Question 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

Solution:

(c) Constellation is a group of stars, so it is not a part of the solar system.

Question 2: Which of the following is NOT a planet of the sun?

(a) Sirius

(b) Mercury

(c) Saturn

(d) Earth

Solution

(a) Sirius is a star.

Question 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.

Solution

(a) The moon reflects the sunlight falling on it. We see only the illuminated part of the moon. The keeps on rotating on its axis. So, the light falling on it also keeps on changing.

Question 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 _________.

Solution

(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 a satellite_.

(e) Shooting stars are actually not stars __.

(f) Asteroids are found between the orbits of __Mars __ and __Jupiter.

Question 5: Mark the following statement 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. ( )

Solution

(a) False. Star is not a member of the solar system. Only sun and the planets are a part of solar system.

(b) True

Mercury is the smallest planet in the solar system.

(c) False

Neptune is the farthest planet in the solar system.

(d) True

INSAT is an artificial satellite.

(e) False

The solar system contains eight planets.

(f) False. Orion can be seen easily with naked eyes.

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

Solution

(i) Inner planets: (e) Mars, (g): earth

(ii) Outer planets: (a) Saturn

(iii) Constellation: (c)Great bear, (f) Orion

(iv) Satellite of the Earth: (d) Moon

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

Solution: It can be seen in the western part of the sky.

Question 8: Name the largest planet of the solar system.

Solution: Jupiter is the largest planet in our solar system.

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

Solution: It is a group of stars that forms a pattern in the sky. Ursa Major and Orion are two constellations.

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

Solution

(a) Ursa Major looks like a big dipper.

(b) Orion has eight stars in the following pattern.

Question 11: Name two objects other than planets that are members of the solar system.

Solution

(a) Asteroids: Collection of a large number of small objects made up of gas and dust.

(b) Meteors: Small celestial objects that can be seen as bright streaks of light.

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

Solution: The position of the pole star can be located with the help of Ursa major. Consider the two stars at the end of the bowl of the Ursa major. Drawing an imaginary straight line towards the Northern direction connects these two stars to the pole star.

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

Solution: Due to the rotation of the earth from west to east. All stars appear to move except the pole star which lies above the axis of rotation of the earth in the north direction.

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?

Solution: The distance between the stars is lakhs of kilometres which is very difficult to express. So, a light-year is used to express the distance between the stars. One light-year is the distance travelled by the light in a year.

A star is located eight light-years away from the Earth means light takes 8 years from that star to reach the earth.

Distance of star from the earth = 8 × (9.46 × 10¹²) = 7.6 × 10¹³ km

Question 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?

Solution

Radius of Earth = R_E

Radius of Jupiter= R_J = 11R_E

1331 Earth can be accommodated in Jupiter.

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

Solution: The positions of Mars and Venus and also the positions of Uranus and Neptune are incorrect. The asteroid belt is located between the orbits of Mars and Jupiter. The correct sequence is Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

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