RBSE Solutions Class 7 Science Chapter 12 Earth Moon and the Sun

Class 7 Science Curiosity Chapter 12 Question Answer (Exercise)

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Question 1. 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: According to Fig. 12.17, the south pole receives more than 12 hours of sunlight. In contrast, the north pole receives less than 12 hours of sunlight during one Earth rotation. This difference is due to the Earth's axial tilt.
In simple words: The south pole gets more than 12 hours of sun, while the north pole gets less than 12 hours.

🎯 Exam Tip: When describing Earth's phenomena related to sunlight, always consider the Earth's tilt and its position relative to the Sun.

Question 2. Fill in the blanks.
(i) Stars rise in the ______ and set in the ______
(ii) Day and night are caused by the Earth's ______
(iii) When the Moon fully covers the Sun from our view, it is called a ______ solar eclipse.
Answer:
(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. This blocks the Sun's light completely.
In simple words: Stars appear from the east and go down in the west. Earth spinning causes day and night. A total solar eclipse happens when the Moon completely blocks the Sun.

🎯 Exam Tip: Remember key terms like 'rotation' for day/night and 'total' for a complete solar eclipse. Knowing the basic movements of celestial bodies helps in understanding these phenomena.

Question 3. State whether True or False.
(i) Lunar eclipse occurs when the Sun comes between the Earth and the Moon.
(ii) Sunrise happens earlier in Gujarat than in Jharkhand.
(iii) In Chennai, the longest day occurs on the summer solstice.
(iv) We should watch the solar eclipse directly with our naked eye.
(v) Seasons occur due to the tilt of Earth's axis of rotation and its spherical shape.
(vi) The Earth's revolution around the Sun causes day and night.
Answer:
(i) **False**
In simple words: A lunar eclipse happens when the Earth is between the Sun and the Moon, not the Sun being in the middle.

🎯 Exam Tip: Understand the correct alignment of Sun, Earth, and Moon for both lunar and solar eclipses to avoid common misconceptions.

Question 4. Padmashree saw the Orion constellation nearly overhead at 8 PM yesterday. When will she see Orion overhead today?
Answer: Padmashree will see the Orion constellation nearly overhead 4 minutes earlier today than yesterday. This means she will see it at 7:56 PM today. This slight shift happens because Earth revolves around the Sun, changing our perspective of the stars.
In simple words: She will see Orion overhead at 7:56 PM today, which is 4 minutes earlier than yesterday.

🎯 Exam Tip: Remember that stars appear to shift positions by about 4 minutes each day due to Earth's orbit around the Sun. This is important for understanding sidereal time.

Question 5. 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: The Earth completes one full revolution around the Sun in about one year. Therefore, Nandhini will see the same group of stars rising at midnight next year on the same date, which is June 21. This consistency is due to Earth's predictable orbit.
In simple words: She will see the stars rise at midnight on June 21 again next year because the Earth's orbit takes one year.

🎯 Exam Tip: Stellar patterns observed at a particular time and date repeat approximately annually, as Earth returns to a similar orbital position.

Question 6. Abhay noticed that when it was daytime in India, his uncle who was in LISA was generally sleeping as it was night-time there. What is the reason behind this difference?
Answer: This difference is due to the Earth's rotation. When the part of Earth where India is located faces the Sun, it experiences daytime. The American part (USA) is on the opposite side, facing away from the Sun, which causes it to be night-time. Earth's rotation continuously changes which part faces the Sun.
In simple words: Day and night are different in India and America because the Earth spins. When one side faces the Sun, it's day, and the other side is night.

🎯 Exam Tip: Understand that Earth's rotation is the primary cause of day and night, and different longitudes experience these at different times.

Question 7. Four friends used the following ways to see solar eclipse. Who among them was being careless?
(i) Ravikiran used a solar eclipse goggle
(ii) Jyothi used a mirror to project the Sun's image
(iii) Adithya saw the Sun directly with his eyes
(iv) Aruna attended a programme arranged by a planetarium
Answer: Adithya was being careless because he saw the Sun directly with his eyes. This is very dangerous and can cause permanent eye damage, as the intense solar radiation is harmful. The other methods are safe ways to observe an eclipse.
In simple words: Adithya was careless because he looked at the Sun directly with his eyes, which is very dangerous for eyesight.

🎯 Exam Tip: Never look directly at the Sun during a solar eclipse without proper protective eyewear, as it can cause serious and permanent eye damage.

The following diagrams illustrate Solar and Lunar eclipses:

Question 9. The Moon is much smaller than the Sun, yet it can block the Sun completely from our view during a solar eclipse. Why is it possible?
Answer: This is possible because the Moon is much closer to the Earth than the Sun is. Even though the Moon is physically much smaller than the Sun, its closeness makes it appear to be the same size in the sky. This allows the Moon to perfectly block the Sun's light during a total solar eclipse, creating an illusion of equal size.
In simple words: The Moon looks as big as the Sun during an eclipse because it is much closer to us, even though it's actually much smaller.

🎯 Exam Tip: Remember that apparent size in the sky depends on both actual size and distance. This concept is key to understanding why eclipses occur as they do.

Question 10. The Indian cricket team matches in Australia are often held in December. Should they pack winter or
Answer: Since Australia is in the Southern Hemisphere, December marks the beginning of their summer season. Therefore, the Indian cricket team should pack summer clothing. This is opposite to the Northern Hemisphere, where December is winter. Seasons are reversed due to Earth's axial tilt and orbit.
In simple words: The team should pack summer clothes because December is summer in Australia, which is in the Southern Hemisphere.

🎯 Exam Tip: Always remember that seasons are opposite in the Northern and Southern Hemispheres. If it's winter in one, it's summer in the other.

Question 11. Why do you think lunar eclipses can be seen from a large part of the Earth when they happen, but total solar eclipse can be seen by only a small part of the Earth?
Answer: Lunar eclipses can be seen from a large part of the Earth because the Earth's shadow, which falls on the Moon, is much larger than the Moon itself. In contrast, during a total solar eclipse, the Moon's shadow that falls on the Earth is relatively small. The Earth is a much larger body than the Moon, so its shadow covers a wider area on the Moon, making lunar eclipses visible to more people.
In simple words: Lunar eclipses are seen by many because Earth's shadow is big. Solar eclipses are seen by few because the Moon's shadow on Earth is small.

🎯 Exam Tip: The size of the shadow cast by the eclipsing body determines how widely an eclipse is visible. Earth's large size creates a broad shadow during a lunar eclipse.

Question 12. If the Earth's axis is 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 with respect to its orbital plane, the Sun's rays would fall equally on all parts of the Earth throughout the year. This means there would be no variation in the amount of sunlight received by different regions at different times. Consequently, the cycle of seasons would not exist, and the same season would persist all year long everywhere. The tilt of the Earth's axis is the primary cause of seasons.
In simple words: If Earth's axis wasn't tilted, sunlight would be even everywhere all year. There would be no seasons, and it would be the same weather always.

🎯 Exam Tip: Remember that the tilt of the Earth's axis is the fundamental reason for the occurrence of seasons, not the distance from the Sun.

Earth Moon and the Sun Class 7 Questions and Answers (Intext)

(Page No. 172)

Question 1. How day and night occur on the Earth due to its rotation?
Answer: The cycle of day and night occurs because of the Earth's rotation from west to east. As the Earth spins, the part of our planet facing the Sun experiences daylight, while the part facing away from the Sun is in darkness, which is night. This continuous spinning creates the regular rhythm of day and night. One full rotation takes about 24 hours.
In simple words: Day and night happen because the Earth spins. The side facing the Sun has day, and the side facing away has night.

🎯 Exam Tip: Emphasize that Earth's rotation, not its revolution, causes the daily cycle of day and night.

(Page No. 174)

Question 2. Since the Earth is rotating, shouldn't the stars also appear to move in the sky like the Sun?
Answer: Yes, since the Earth is rotating on its axis, stars also appear to move across the sky, similar to the Sun. This apparent movement is entirely due to our perspective from the rotating Earth. Additionally, because the Earth is revolving around the Sun, our view of the stars also changes slightly over the course of a year, leading to different constellations being visible at different seasons.
In simple words: Yes, because Earth spins, stars seem to move across the sky, just like the Sun. This movement is what we see from our spinning planet.

🎯 Exam Tip: Understand that most observed celestial motion (Sun, Moon, stars) is an apparent motion caused by Earth's own movements: rotation (daily) and revolution (yearly).

(Page No. 177)

Question 4. We go through a cycle of seasons every year. Is it related to the revolution of the Earth around the Sun in some way?
Answer: Yes, the annual cycle of seasons is directly related to the Earth's revolution around the Sun. This occurs because the Earth's axis of rotation is tilted, not straight up, compared to its orbital path. The Earth keeps this tilt as it moves around the Sun, so different parts of the Earth get more direct sunlight at different times of the year, causing the change in seasons.
In simple words: Yes, seasons happen because Earth moves around the Sun while its axis is tilted. This tilt changes how much direct sunlight different parts get throughout the year.

🎯 Exam Tip: Always link seasons to two factors: Earth's revolution around the Sun AND the tilt of its axis. Both are essential.

(Page No. 179)

Question 5. Could the light from the Sun get blocked by the two planets which are revolving between the Earth and the Sun?
Answer: Planets like Mercury and Venus, which orbit between the Earth and the Sun, cannot block the Sun's light to cause an eclipse on Earth. This is because they are comparatively very far from the Earth. Only the Moon, despite being smaller than these planets, is close enough to Earth to block the Sun's light and cause a solar eclipse. The Moon's proximity makes its apparent size similar to the Sun's from Earth's perspective.
In simple words: Mercury and Venus cannot block the Sun's light to cause an eclipse on Earth because they are too far away. Only the Moon is close enough to do this.

🎯 Exam Tip: The ability of a celestial body to cause an eclipse depends on its angular size (apparent size from Earth), which is influenced by both its actual size and its distance from the observer.