Class 7 Science Chapter – 12 Earth, Moon, and the Sun Questions and Answers
Let Us Enhance Our Learning Page no: 184
Q1. In Fig. 12.17, how many hours of sunlight do the North Pole and the South Pole receive during one rotation of the Earth?
Answer: In the figure (June position), the North Pole is tilted towards the Sun, so it receives sunlight for all 24 hours during one rotation. The South Pole, tilted away from the Sun, receives 0 hours of sunlight — it remains in darkness for all 24 hours.
Q2. Fill in the blanks
(i) Stars rise in the east and set in the west.
(ii) Day and night are caused by the Earth’s rotation.
(iii) When the Moon fully covers the Sun from our view, it is called a total solar eclipse.
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Q3. State whether True or False
Answer:
(i) Lunar eclipse occurs when the Sun comes between the Earth and the Moon. — False (A lunar eclipse occurs when the Earth comes between the Sun and the Moon.)
(ii) Sunrise happens earlier in Gujarat than in Jharkhand. — False (Jharkhand lies to the east of Gujarat, and sunrise occurs first in the eastern part of India.)
(iii) In Chennai, the longest day occurs on the summer solstice. — True
(iv) We should watch the solar eclipse directly with our naked eye. — False (Looking at the Sun directly is harmful; use safe methods like solar eclipse goggles or projected images.)
(v) Seasons occur due to the tilt of Earth’s axis of rotation and its spherical shape. — True
(vi) The Earth’s revolution around the Sun causes day and night. — False (Day and night are caused by the Earth’s rotation.)
Q4. Padmashree saw the Orion constellation nearly overhead at 8 pm yesterday. When will she see Orion overhead today?
Answer: Because of the Earth’s revolution around the Sun, the night sky shifts slightly each day. The same star pattern appears about 4 minutes earlier each day. So Padmashree will see Orion nearly overhead at about 7:56 pm today.
Q5. Nandhini saw a group of stars rising at midnight on 21 June. When will she see the same group of stars rising at midnight next year?
Answer: She will see the same group of stars rising at midnight on 21 June next year (approximately). Since the Earth completes one revolution around the Sun in about 365 days and 6 hours, the same view of the night sky at the same time of night repeats after roughly one year.
Q6. Abhay noticed that when it was daytime in India, his uncle in the USA was generally sleeping as it was night-time there. What is the reason behind this difference?
Answer: The Earth rotates from West to East. At any moment, the half of the Earth facing the Sun experiences day, while the opposite half experiences night. India and the USA lie on nearly opposite sides of the Earth, so when India faces the Sun (daytime), the USA is on the dark side (night-time).
Q7. Four friends used the following ways to see the solar eclipse. Who among them was being careless?
Answer: Adithya was being careless, because he saw the Sun directly with his eyes. This is dangerous — the Sun’s rays can damage the eyes. The safe methods are solar eclipse goggles, projecting the Sun’s image with a mirror, or watching a planetarium programme.
Q8. Fill in the circles in Fig. 12.18 appropriately with Sun, Moon, or Earth.
Answer:
- Solar eclipse: the arrangement is Sun → Moon → Earth (the Moon is between the Sun and the Earth).
- Lunar eclipse: the arrangement is Sun → Earth → Moon (the Earth is between the Sun and the Moon).
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Q9. The Moon is much smaller than the Sun, yet it can block the Sun completely from our view during a total solar eclipse. Why is it possible?
Answer: The Moon is much closer to the Earth than the Sun is. Because of this small distance, the Moon appears almost the same size as the Sun in our sky, just like a thumb held close can cover a friend’s entire head standing far away (Activity 12.4). So when the Moon comes exactly between the Sun and the Earth, it can cover the Sun’s disc completely, causing a total solar eclipse.
Q10. The Indian cricket team matches in Australia are often held in December. Should they pack winter or summer clothes for their trip?
Answer: They should pack summer clothes. Australia is in the Southern Hemisphere, where the seasons are reversed compared to the Northern Hemisphere. December is winter in India but summer in Australia.
Q11. Why do you think lunar eclipses can be seen from a large part of the Earth when they happen, but a total solar eclipse can be seen by only a small part of the Earth?
Answer: During a lunar eclipse, the Earth’s shadow falls on the Moon, and the Earth’s shadow is much larger than the Moon. The Moon passes through this large shadow, so the eclipse is visible from wherever the Moon is visible — a large part of the Earth. In a solar eclipse, it is the Moon’s small shadow that falls on the Earth, covering only a small area of the Earth’s surface, so only observers in that small patch see the total solar eclipse.
Q12. If the Earth’s axis were not tilted with respect to the axis of revolution, explain what would be the effect on seasons?
Answer: If the Earth’s axis were not tilted, both hemispheres would receive nearly the same amount and intensity of sunlight throughout the year. There would be no distinct seasons like summer and winter — the day length would be about 12 hours everywhere all year, and the climate at a place would stay nearly the same throughout the year.