Something to Know
A. Fill in the blanks.
1. A group of stars that appear to form a pattern in the sky is known as a constellation.
2. A planet is nearer to us than the stars.
3. The planets are also known as wandering stars.
4. The pole star defines the North direction.
5. Stars twinkle but planets do not twinkle.
B. Match the following:
1. a constellation visible in winter c. Orion
2. the ‘morning stars’ e. Mercury and Venus
3. a constellation visible in spring d. Ursa Minor
4. the brightest object in the night sky b. Moon
5. a star of average brightness a. Sun
C. Tick (✔) the correct option.
1. The planet that can be (sometimes) seen in the evening sky, even with unaided eye, is-
(a) Neptune
(b) Saturn (✔)
(c) Mercury
(d) Uranus
Answer – (b) Saturn (✔)
2. The two stars, at the top of Ursa Major, are called-
(a) Pole Stars
(b) Big Dipper
(c) Small Dipper
(d) Pointers (✔)
Answer – (d) Pointers (✔)
3. The Cassiopeia is-
(a) a bright group of stars in the sky.
(b) an artificial satellite.
(c) the name given to a spacecraft.
(d) a constellation visible in autumn. (✔)
Answer – (d) a constellation visible in autumn. (✔)
4. From the following, the object in the sky, that (apparently) moves least in a given time is-
(a) North Star (✔)
(b). Venus
(c) Sun
(d) Moon
Answer – (a) North Star (✔)
5. The brightest planet in the night sky is-
(a) Jupiter (✔)
(b) Venus
(c) Mars
(d) Neptune
Answer – (a) Jupiter (✔)
6. On closely observing some bright stars, for some hours, one finds that stars appear to move from—
(a) east to west (✔)
(b) west to east
(c) north to south
(d) south to north
Answer – (a) east to west (✔)
D. Answer the following questions in brief.
1. Why do, we usually not see the stars during the day?
Answer – We usually cannot see the stars during the day because of the brightness of the sun.
2. In which part of the sky are we likely to find Venus when it is visible as an evening star?
Answer – Venus can be seen very low near the horizon in the sky in the evening.
3. State the cause of the apparent motion of the sun from east to west?
Answer – The sun appears to be moving from east to west due to the rotation of the earth from west to east in its axis.
4. Name the special star in the northern hemisphere. Why has it been useful for travellers?
Answer – The special star in the Northern hemisphere is the pole star. It has been useful for travelers because it defines the north direction.
E. Answers the following questions.
1. Define the term ‘constellation’.
Answer – A constellation is a group of stars that appear to form some recognisable pattern or shape in the sky.
2. In what respects is, the pole star, different from other stars?
Answer – Pole star, unlike other stars, appears to remain fixed at one place. This is so because it lies almost along the axis of rotation of the earth. It defines the north direction.
3. Write two points of difference between a planet and a star.
Answer – (i)A planet is closer but the stars are very far from us.
(ii)A planet doesn’t have its own light but stars have their own light.
4. Why do stars appear to slightly shift their position in the night sky?
Answer – Stars appear to slightly shift their position in the night sky because of the rotation of the earth on its axis from west to east.
5. Why do stars appear as points to us?
Answer – Stars appear as points to us because of their large distance from the earth.
Value Based Question
Dhruv is studying in a reputed public school of Delhi. His grandparents live in a small town at the foothills of the Himalayas. During summer vacation he visited his grandparents. He behaved in a very polite and nice way and was very respectful of towards his grandparents. In night, he was amazed to see very large number bright stars twinkling in the night sky. His grandfather showed him various groups of star forming some beautiful patterns. He was very excited to see these beautiful patterns of stars, which he was not able to see in Delhi.
1. Do you think that pollution in atmosphere effects the natural phenomenon of twinkling of stars?
Answer – Yes, pollution affects the natural phenomenon of twinkling of stars. Stars are not nicely visible in polluted sky.
2. How did Dhruv behave with his grandparents? Share your own similar experiences with your friends.
Answer – Dhruv behaved very politely, nicely and respectfully with his grandparents. When I visit my grandparents’ place, I also visit their farms which are full of greenery.
3. State the name of one group of stars forming a familiar pattern seen in summer.
Answer – Scorpius can be seen in summer.
Something to Do
1. Try to locate Venus in the night sky. Find out from newspaper reports when Venus is likely to be visible.
Answer – Students will do this at their own.
2. After sunset go, with your parents, to some large open ground from where the horizon is clearly visible. Look at a rising star. Mark its direction with respect to a pole or a tree. Next day go to the same spot a little earlier and observe the same star from the same position. Repeat, and tabulate, your observations for a few days. Discuss your findings with your teacher or friends.
Answer – Students will do this at their own.
By Sunaina Karmakar