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Q1 Which of the following is NOT a member of the solar system? (a) An asteroid (b) A satellite (c) A constellation (d) A comet Ans: (c) A constellation
A constellation is not a member of the solar system. Group of stars with a recognizable pattern in the sky are called as constellation.
Q2 Which of the following is NOT a planet of the sun? (a) Sirius (b) Mercury (c) Saturn (d) Earth Ans: (a) Sirius
Sirius is a planet of the sun. It is not a star.
Q3 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 moon’s surface. (d) the thickness of the moon’s atmosphere is not constant. Ans: (a) We can see only that part of the moon which reflects light towards us.
Moon does not have its own light. When sunlight falling of then it gets reflected towards us. So, only that part of the moon appear to us which reflects the light of sun towards us.
Q4 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 _________ . Ans: (a) Neptune
Neptune is present far away from the sun.
(b) Mars
Because on Mars, a lot of rocks and iron parts are present, when they come in contact of air, they get oxidized and turn into reddish colour.
(c) Constellation
Constellation is a group of stars with a recognizable pattern in the sky.
(d) Satellite
Satellite gives scientific information about the planet and it is a source of communication also.
(e) Stars
They are actually not stars, they are meteors.
(f) Mars, Jupiter
Asteroids occupy a large gap between the orbits of Mars and Jupiter.
Q5 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. ( ) Ans: (a) False
This statement is false because stars are not the member of the solar system.
(b) True
This statement is true because the smallest planet of the solar system is Mercury.
(c) False
This statement is false because Neptune is the farthest planet of the solar system.
(d) True
Yes, it is an artificial satellite. It is man- made satellite. Hence, this statement is true.
(e) False
This statement is false because there are eight planets in our solar system.
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
(f) False
This statement is false because constellation Orion is large enough to see with naked eyes.
Q6 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 Ans: A B
(i) Inner planets (a) Saturn
(ii) Outer planets (b) Pole star
(iii) Constellation (c) Great Bear, (f) Orion
(iv) Satellite of the Earth (d) Moon
Q7 In which part of the sky can you find Venus if it is visible as an evening star? Ans: Venus become visible after sunset that is why it is called evening star. It appears in the west direction.
Q8 Name the largest planet of the solar system. Ans: Jupiter is the largest planet of the solar system.
Q9 What is a constellation? Name any two constellations. Ans: Constellation: The stars forming a group that has a recognizable shape or pattern in the sky is called constellation. For example: Great bear (Ursa Major), Orion etc.
Q10 Draw sketches to show the relative positions of prominent stars in (a) Ursa Major and (b) Orion Ans: (a) In Ursa major, for stars are present in the bowl and the three stars in the handle. It appears like a big dipper.
(b) Orion: It appears like a hunter. In this, five stars are arranged in a form of quadrilateral and three stars appears in the belt.
Q11 Name two objects other than planets which are members of the solar system. Ans: Asteroids and meteors are the two objects other than planets which are the member of the solar system.
- Asteroids: It is a collection of gases, dirt and small objects which are revolving around the sun. In between the orbits of Mars and Jupiter, asteroids occupies an large gap. Asteroids are celestial objects not planets.
- Meteors: These are small celestial objects that can be seen as a bright streaks of light in the sky. Because of the heat produced by friction, meteors are burnt out when they enters into the earth’s atmosphere. This may lead to a bright streaks in the sky. Hence, we can say that they are not planets.
Q12 Explain how you can locate the Pole Star with the help of Ursa Major. Ans: Look at the two stars at the end of the Ursa Major. Imagine a straight line passing through these stars. Extend this imaginary line towards the north direction. At the point where the imaginary line meets to a star is called the pole star.
Q13 Do all the stars in the sky move? Explain. Ans: No, all the stars in the sky do not move. They only appear to move. This is because earth moves from west to east. Like when we travel in the train, the nearby trees and building appears to move in the backward direction.
Q14 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? Ans: Stars at a distance of millions of kilometers from the earth. Thus, there large distance are expressed in the light year. One light year is the distance travelled in one year.
One light year = 9.46 x 1012 km.
If a star is located eight years away from the earth that means the distance between the star and the earth is equal to the distance which is travelled by light in eight years. So, the distance between the star and the earth us given by:
8 x (9.46 x 1012) km = 7.6 x 1012 km.
Q15 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? Ans: Q16 Boojho made the following sketch (Fig. 17.29) of the solar system. Is the sketch correct? If not, correct it. Ans: Position of Mars, Venus, Uranus and Neptune should be interchanged. The correct position of the planets are as follows:
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.