A. Fill in the blanks
1. Question: A group of stars that appear to form a pattern in the sky is known as a __________.
Answer: A group of stars that appear to form a pattern in the sky is known as a constellation.
2. Question: A planet is __________ to us than the stars.
Answer: A planet is nearer to us than the stars.
3. Question: The planets are also known as __________.
Answer: The planets are also known as wandering stars.
4. Question: The pole star defines the __________ direction.
Answer: The pole star defines the north direction.
5. Question: Stars __________ but planets do not __________.
Answer: Stars twinkle but planets do not twinkle.
B. Match the following:
Question: Match the following:
1. A constellation visible in winter — Orion
2. The ‘morning stars’ — Mercury and Venus
3. A constellation visible in spring — Ursa Minor
4. The brightest object in the night sky — Moon
5. A star of average brightness — Sun
C. Tick (✔) the correct option
1. Question: The planet that can be sometimes seen in the evening sky, even with unaided eye, is—
Answer: (c) Mercury
2. Question: The two stars at the top of Ursa Major are called—
Answer: (d) Pointers
3. Question: The Cassiopeia is—
Answer: (d) a constellation visible in autumn
4. Question: From the following, the object in the sky that apparently moves least in a given time is—
Answer: (a) North Star
5. Question: The brightest planet in the night sky is—
Answer: (b) Venus
6. Question: On closely observing some bright stars for some hours, one finds that stars appear to move from—
Answer: (a) east to west
D. Answer the following questions in brief :
1. Question: Why do we usually not see the stars during the day?
Answer: We do not see stars during the day because the bright sunlight hides their faint light.
2. Question: In which part of the sky are we likely to find Venus when it is visible as an evening star?
Answer: Venus is seen in the western part of the sky as an evening star.
3. Question: State the cause of the apparent motion of the sun from east to west.
Answer: The apparent motion of the sun is caused by the rotation of the Earth from west to east.
4. Question: Name the special star in the northern hemisphere. Why has it been useful for travellers?
Answer: The Pole Star is the special star. It helps travellers to find the north direction.
E. Answer the following questions:
1. Question: Define the term ‘constellation’.
Answer: A constellation is a group of stars that form a recognizable pattern in the sky.
2. Question: In what respects is the pole star different from other stars?
Answer: The pole star appears almost fixed in position and always indicates the north direction.
3. Question: Write two points of difference between a planet and a star.
Answer:
(i) Stars have their own light, planets do not.
(ii) Stars twinkle, planets do not twinkle.
4. Question: Why do stars appear to slightly shift their position in the night sky?
Answer: Stars appear to shift because of the rotation of the Earth.
5. Question: Why do stars appear as points to us?
Answer: Stars appear as points because they are very far away from the Earth.
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