Choose the correct answer in Question 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

Q2. Which of the following is NOT a planet of the sun?

(a) Sirius (b) Mercury

(c) Saturn (d) Earth

Answer – (a) Sirius

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 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.

Q4. 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 __________.

Answer- constellation

(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

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.

Answer-

(a) Pole star is a member of the solar system. (F)

(b) Mercury is the smallest planet of the solar system. (T)

(c) Uranus is the farthest planet in the solar system. (F)

(d) INSAT is an artificial satellite. (T)

(e) There are nine planets in the solar system. (F)

(f) Constellation Orion can be seen only with a telescope. (F)

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

Answer-

Q7. In which part of the sky can you find Venus if it is visible as an evening star?

Answer- We can find Venus in the west side of the sky if it is visible as an evening star.

Q8. Name the largest planet of the solar system.

Answer- Jupiter.

Q9. What is a constellation? Name any two constellations.

Answer- A constellation is a group of stars that appears to form a recognisable shape. Orion, Ursa Major are examples of the constellation.

Q10. Draw sketches to show the relative positions of prominent stars in

(a) Ursa Major and (b) Orion

Answer-

Q11. Name two objects other than planets which are a member of the solar system.

Answer- Comet, Asteroids and Meteors.

Q12. Explain how you can locate the Pole Star with the help of Ursa Major.

Answer- To locate the pole star in the sky with the help of Ursa Major, we should use two stars at the end of Ursa Major. The bowl of big dipper consists of four bright stars.

Draw an imaginary straight line towards the Northern direction connecting these two stars.

This imaginary line meets a star called pole star. This line is about five times the distance between two stars.

Q13. Do all the stars in the sky move? Explain.

Answer- No, all the stars don’t move in the sky. The stars in the sky appear to move because of the rotation of Earth on its axis.

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?

Answer- The distance of stars from Earth is quite very large and hence it is not convenient to express the distance in Km. So, such large distances are expressed in a light year.

Light year- The distance travelled by light in a year is called a light-year.

Speed of light- 3,00,000 Km/ Sec

1 light year = 3,00,000 x  ( 365 x 24 x 60 x 60 ) Km

                       = 9.46 x  1012   Km
 

If we say the star is eight light-years away from earth, it means the light from that star will reach the Earth in eight years.

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 accommodate?

Answer-

Let, Radius of Earth be R.

The radius of Jupiter is R1

So, R1= 11R

Volume of Earth = 

Volume of Jupiter =

                           = 

                          = 

Ratio = Volume of Jupiter/ Volume of Earth =

                                                                         =1331

Hence, 1331 Earth can accommodate with Jupiter.