Class 8 is an important phase of a student's life, in class 8 many new topics and chapters are added. Topics like solar system and stars are taught to students so that they can know about the different planets and stars . To score good marks in class 8 science examination one should try to solve the NCERT questions provided at the end of each chapter.
NCERT solutions for class 8 science chapter 17 pdf is provided here for better understanding of the chapter.
From the following pick out, which is not the member of the solar system?
a) A satellite
b) A comet
c) An asteroid
d) A constellation
d) A constellation
A constellation is not the member of the solar system. These are the group of stars that forms a recognizable shape is known as Constellation.
Which is not a planet of the sun from the following?
It is not the planet of the sun but it is a star.
What is the reason behind the phases of the moon?
a) Continuous changing of the distance of the moon from us
b) The thickness of the moon’s atmosphere is variable
c) We can see only that part of the moon which reflects light towards us.
d) Only the part of the moon’s surface is covered by the Earth’s shadow
c) We can see only that part – of the moon, which reflects light towards us.
Moon does not have its own light. It is only be seen by us when sunlight falls on the moon and gets reflected towards us. So, we can only see the part of the moon on which the sunlight falls and reflects towards us.
Complete the following sentences:
a) Farthest planet from the sun is _________.
b) ________ are not actually shooting stars.
c) The planet whose color is red is _______.
d) ________ are the celestial body that revolves around the planet.
e) ________ are the group of stars that appears to form a pattern in the sky.
f) Asteroids are found between the orbits of _______ and _____.
a) Farthest planet from the sun is Neptune.
b) Shooting stars are not actually stars.
c) The planet whose color is red is Mars.
d) Satellites are the celestial body that revolves around the planet.
e) Constellation is the group of stars that appears to form a pattern in the sky.
f) Asteroids are found between the orbits of Mars and Jupiter.
State True and False against the following sentences:
- The farthest planet in the solar system is Uranus. ( )
- We can see constellation Orion with the help of a telescope. ( )
- The smallest planet of the solar system is mercury. ( )
- INSAT is said to be known as an artificial satellite. ( )
- The total number of planets in the solar system is nine. ( )
- Polestar is a member of the solar system. ( )
- The farthest planet in the solar system is Uranus. (False)
The farthest planet in the solar system is Neptune.
- We can see constellation Orion with the help of a telescope. (False)
During winters in the late evening, we can able to see constellation Orion. It seems to be the most beautiful constellation in the sky which can be seen through naked eyes.
- The smallest planet of the solar system is mercury. (True)
- INSAT is said to be known as an artificial satellite. (True)
- The total number of planets in the solar system is nine. (False)
The total number of planets in the solar system is eight; these are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
- Pole star is a member of the solar system. (False)
Stars are not the members of the solar system. The sun and the celestial bodies revolving around it in the solar system.
Match the followings from column A with column B.
|i) Outer planets||a) Earth|
|ii) Inner planets||b) Orion|
|iii) Satellites of the Earth||c) Mars|
|iv) Constellation||d) Pole star|
|f) Great Bear|
|i) Outer planets||g) Saturn|
|ii) Inner planets||a), c) Earth, Mars|
|iii) Satellites of the Earth||e) Moon|
|iv) Constellation||b), f) Orion, Great Bear|
The planet Venus is found in which part of the solar system, if it is visible as an evening star?
The planet Venus is found in the western part of the sky after sunset and is said to be known as an evening star.
Which planet is largest in the solar system?
Jupiter is the largest planet in the solar system.
What do you mean by constellation? Name any two.
The group of stars that forms a recognizable pattern in the sky is known as constellation.
Two constellations are;
Draw the diagram that shows the relative position of prominent stars a) Orion b) Ursa Major
a) Orion seems to be like a hunter. The three bright stars appear in the belt, while five bright stars are arranged in the form of a quadrilateral.
b) Ursa Major seems to be like a big dipper. There are four stars in the bowl of the dipper and three bright stars in the handle.
Name the two objects other than planets, which are members of the solar system?
Meteors are small celestial objects that are seen as bright streaks of light in the sky. Due to the heat produced by the friction of the Earth’s atmosphere, the Meteors are burnt out while entering in, this causes the bright streaks in the sky. They are not planets.
The Asteroids are the collection of a huge number of small objects; gasses and dust are revolving around the sun. Between the orbits of Mars and Jupiter, they occupy the large gap. These are not planets. They are the celestial bodies and are known as Asteroids.
With the help of Ursa Major, how can you locate the pole star?
For locating, the pole stars in the sky, first the big dropper or the Ursa Major constellation must be found out. The bowl of the big dipper consists of the four bright stars.
Imagine the two stars at the end of this bowl. Then make an imaginary straight line towards the northern direction connecting these two stars.
This imaginary line meets the star called Pole star. The length of the imaginary line from the bowl is about five times the distance between the two stars of the bowl.
Do you think that all the stars in the sky moves? Explain.
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.
Why is the distance between the stars expressed in light years? Clearly, elaborate the statement that “the star is eight light years away from the Earth.”
The distance of the star from the earth and the distance between the stars are very huge. It is troublesome to express these distance in kilometer (km). Therefore, these huge distances are expressed in light years. One light year is equal to the distance traveled by the light in one single year. One light year is equal to 9.46 x 1012 km.
A distance of the star from the Earth is eight light year. This means the distance between them is equal to the distance traveled by the light in eight years, i.e. distance of the star is 8 x (9.6 x 1012) = 7.6 x 1013 km away from Earth.
The radius of Jupiter is 11 times bigger than the Earth. Calculate the ratio of the volumes of Jupiter and the Earth. So, how many Earth can fit the Jupiter?
Let us consider Jupiter and Earth are two spheres with radii R and R’ respectively. Given in the question that radius of Jupiter is 11 times the radius of the Earth.
So, R’= 11R
Volume of sphere of radius r is given as =
Volume of Earth =
And, volume of Jupiter =
The ratio of the volume of Jupiter and earth
Therefore, this ratio suggests that Jupiter can fit 1331 number of Earth in it.
Vikram has made the diagram of the solar system. Do you think the diagram he had made is correct? If not, correct it.
No, the diagram made by the Vikram is not correct, because in the solar system the planets sequence of their distance from the sun is like; Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. The mistake he had done is he changes the positions of the planets Venus, Mars, Neptune and Uranus. Besides this, he had shown in the diagram that the Asteroids belt in the gap between the orbits of Saturn and Jupiter. This is incorrect. The Asteroids belt is located in the middle of the orbits of Jupiter and Mars. The correct diagram of the solar system is given below: