Stars and the Solar System-NCERT Solutions

Class VIII Science
NCERT Solution for Stars and the Solar System
Q.1.   Which of the following is NOT a member of the solar system.
            (a) An asteriod
(b) A sate�lite
(c) A constellation
(d) A cornet.
Ans.   (c) A constellation.
Q.2.   Which of the following is NOT a planet of the sun?
            (a) Sirius
(b) Mercury
(c) Saturn
(d) Earth
Ans.   (a) Sirius
Q.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.
Ans.   (a) We can see only that part of the moon which reflects light towards us.
Q.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________.
            (e) Shooting stars are actually not________.
            (f) Asteroids are found between the orbits of ________ and ________.
Ans.   (a) Neptune      (b) Mars      (c) Constellation
            (d) Satellite      (e) meteors      (f) Mars, Jupieter.
Q.5.   Mark the following statements as true or false:
            (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 our solar system.
            (d) INSAT is an artifical satellite.
            (e) There are nine planets in our solar system.
            (f) Constellation Orion can be seen only with the telescope.
Ans.   (a) False       (b) True       (c) False       (d) True
            (e) False       (f) False
Q.6.   Match items in Column A with one or more items of Column B:
Q.7.   In which part of the sky can you find Venus, if it is visible as an evening star?
Ans.   In west side of the sky.
Q.8.   Name the largest planet of the solar system.
Ans.   The largest planet is Jupiter.
Q.9.   What is constellation? Name any two constellations.
Ans.   A group of star which has a recognizable shape is called constellation. Two constellations are great Bear and Orion.
Q.10.   Draw sketch to show the relative position of prominent star in
            (i) Ursa Major         (ii) Orion.
Q.11.   Name two objects other than planets which are members of the solar system.
Ans.   Comets and asteriods.
Q.12.   Explain how you can locate the pole star with the help of Ursa Major.
Ans.   Pole star can be located with the help of the three stars at the end of Ursa Major. Imagine a straight line passing through these stars. Extend the imaginary line in north direction. This line is about five times the distance between two stars. A star is to be seen in this direction. This is pole star.
Fig. 17.9 Pole star is in the direction of earth.
Q.13.   Do all the stars in the sky move? Explain.
Ans.   No, all the stars do not move in the sky. They appears to move from east to west. It is due to the rotation of earth on which we live. The earth moves from west to east. But pole star does not appear to move.
Q.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?
Ans.   Stars are far away from each other. The distance between two stars is millions of kilometers. The distance between sun and earth is 150,000,000 km, whereas the distance of alpha centuary is 40,000,000,000,000 km. It is not convenient to show in km. So it is expressed in light year. A light year is the distance covered by light in one year. Eight light year means the distance covered by light in eight years.
Q.15.   The radius of Jupiter is 11 times the radius of the Earth. Calculate the ratio of the volume of Jupiter and the Earth. How many Earths can Jupiter accommodate?
Ans.   Let the radius of Earth = R units
            Now the ratios of the volume of Jupiter and Earth
            So 1331 Earths can be accommodated in one Jupiter.
Q.16.   Boojho made the solar system (Fig. 17.10). Is the sketch correct? If not, correct it.
Ans.   No, the given sketch is not correct. The following figure is correct.