Extra Questions for Chapter 12 Earth, Moon and the Sun Class 7 Science Curiosity
Class 12 Earth, Moon and the Sun Extra Questions
Very Short Answer Questions
Question 1. What causes day and night on Earth?
Answer
The Earth’s rotation causes day and night.
Question 2. In which direction does the Earth rotate?
Answer
The Earth rotates from West to East.
Question 3. What is the cause of the apparent motion of the Sun in the sky?
Answer
The apparent motion of the Sun is caused by the Earth’s rotation around its axis.
Question 4. What is rotation?
Answer
Rotation is the spinning of an object around its own axis.
Question 5. What is the Earth's axis of rotation?
Answer
It is an imaginary line that passes through the North and South poles.
Question 6. Why is the Moon able to block the Sun during a solar eclipse?
Answer
The Moon is much smaller than the Sun, but it is much closer to the Earth, making it appear to cover the Sun.
Question 7. Why do we experience different seasons on Earth?
Answer
Different seasons occur due to the tilt of the Earth’s axis while it revolves around the Sun.
Question 8. How long does the Earth take to complete one revolution around the Sun?
Answer
The Earth completes one revolution around the Sun in about 365 days and 6 hours.
Question 9. Why do the stars in the night sky change over the course of a year?
Answer
The changing position of the Earth in its orbit around the Sun causes different stars to be visible at different times.
Question 10. What is a lunar eclipse?
Answer
A lunar eclipse occurs when the Earth passes between the Sun and the Moon, casting a shadow on the Moon.
Question 11. What is a solar eclipse?
Answer
A solar eclipse occurs when the Moon passes between the Earth and the Sun, blocking the Sun’s light.
Question 12. What is a partial solar eclipse?
Answer
A partial solar eclipse occurs when the Moon partially blocks the Sun.
Question 13. When does the Northern Hemisphere experience winter?
Answer
In December, when the Northern Hemisphere is tilted away from the Sun.
Question 14. Why should we not look directly at a solar eclipse?
Answer
Directly viewing a solar eclipse can damage the eyes and cause blindness.
Question 15. What happens during the rotation of the Earth on its axis?
Answer
Half of the Earth faces the Sun and experiences daytime, while the other half experiences night-time.
Question 16. How long does the Earth take to complete one revolution around the Sun?
Answer
About 365 days and 6 hours.
Question 17. What causes the seasons on Earth?
Answer
The tilt of the Earth’s axis and its orbit around the Sun causes the seasons.
Question 18. What causes the stars to appear to move in the sky?
Answer
The Earth’s rotation causes the apparent movement of stars.
Question 19. What direction does the Sun appear to move in the sky?
Answer
The Sun appears to rise in the East and set in the West.
Question 20. When does the Northern Hemisphere experience summer?
Answer
In June, when the Northern Hemisphere is tilted towards the Sun.
Question 21. Which is the longest day on earth?
Answer
The longest day is in the Northern Hemisphere, occurring around 21 June.
Question 22. What happens during a solar eclipse?
Answer
The Moon blocks the Sun’s light from reaching the Earth.
Short Answer Questions
Question 1. What is an equinox, and when does it occur?
Answer
An equinox is when day and night are equal (12 hours each), occurring around March 21 (spring equinox) and September 23 (autumn equinox).
Question 2. Why does the Sun appear to rise in the East and set in the West?
Answer
The Sun appears to rise in the East and set in the West because the Earth rotates from West to East. As the Earth rotates, different parts of it move into and out of sunlight.
Question 3. Why do different stars appear in the night sky over the course of a year?
Answer
The position of stars in the night sky changes due to the Earth's revolution around the Sun. As Earth moves along its orbit, the stars visible at night also shift.
Question 4. What is the effect of the Earth’s axial tilt on seasons?
Answer
The Earth’s axial tilt causes different parts of the Earth to receive varying amounts of sunlight throughout the year, leading to the changing seasons.
Question 5. Why do we see different constellations in the night sky during different months?
Answer
As the Earth revolves around the Sun, we face different directions in space. This causes different constellations to be visible at different times of the year.
Question 6. How can we safely observe a solar eclipse?
Answer
A solar eclipse should not be viewed directly with the naked eye. Special protective glasses or indirect methods (like using a mirror to project the image) should be used for safe viewing.
Question 7. What is the effect of the Earth’s tilt on the seasons?
Answer
The tilt of the Earth’s axis, combined with its revolution around the Sun, causes different parts of the Earth to receive varying amounts of sunlight at different times of the year. This variation in sunlight results in the four seasons: spring, summer, autumn, and winter, each with different lengths of days and nights.
Question 8. Describe the process of a solar eclipse and how it occurs.
Answer
A solar eclipse occurs when the Moon passes between the Earth and the Sun, blocking the Sun’s light. The Moon’s shadow falls on the Earth, causing a temporary period of darkness. Depending on the alignment, it can be a total solar eclipse, where the Sun is completely blocked, or a partial solar eclipse, where only a part of the Sun is obscured.
Question 9. What is the significance of the apparent size of the Sun and Moon in enabling a total solar eclipse, and why doesn’t Venus or Mercury cause similar eclipses?
Answer
The Moon and Sun appear almost the same size in the sky because, although the Sun is 400 times larger, it is also 400 times farther from Earth. This coincidence allows the Moon to completely cover the Sun during a total eclipse. Venus and Mercury, though planets, appear much smaller in the sky and cannot block the Sun significantly. Instead, they cause rare events like the Transit of Venus, where they appear as tiny dots moving across the Sun.
Question 10. Why do we always see the same side of the Moon from Earth, even though the Moon revolves around us?
Answer
This happens due to synchronous rotation. The Moon takes the same time to rotate on its axis as it does to orbit the Earth (about 27.3 days). Because of this, the same hemisphere of the Moon always faces Earth. The far side, often called the “dark side,” remains hidden from our view, even though it does receive sunlight during its orbit.
Question 11. Explain the phenomenon of day and night on Earth.
Answer
Day and night occur because the Earth rotates on its axis. As the Earth rotates, one half of the planet faces the Sun, experiencing daylight, while the other half is in darkness, experiencing night-time. This rotation takes approximately 24 hours, causing a complete cycle of day and night.
Question 12. If the Earth revolved around the Sun in 100 days instead of 365, what changes would we observe in seasons and the calendar year?
Answer
With a shorter revolution period, each season would last for about 25 days, drastically reducing their duration. This would impact agriculture, festivals, and climate stability. The calendar year would also shrink to around 100 days, disrupting how we measure time, plan events, and organize economic and academic systems built on a 12-month year.
Question 13. Describe the difference between Earth’s rotation and revolution.
Answer
|
Earth's Rotation |
Earth's Revolution |
|
1. Earth’s rotation refers to its spinning on its axis, taking about 24 hours to complete one rotation. |
1. Earth's revolution is the motion of the Earth around the Sun, taking approximately 365 days and 6 hours to complete one full orbit. |
|
2. This causes day and night. |
2. The revolution is responsible for the changing seasons on Earth. |
Question 14. How did ancient astronomers like Aryabhata explain celestial events without modern technology? What does this tell us about early scientific thinking?
Answer
Aryabhata used keen observation, logical reasoning, and mathematical models to explain phenomena like the Earth's rotation and the apparent motion of stars. He likened celestial motion to viewing stationary objects from a moving boat. His calculations about the Earth's rotation were nearly accurate to modern values. This shows that ancient scholars had strong observational skills and laid the foundation for modern astronomy through intellectual inquiry.
Question 15. Why is the lunar eclipse visible from more parts of the Earth compared to a solar eclipse, even though both involve the alignment of the Earth, Sun, and Moon?
Answer
During a lunar eclipse, the Earth’s shadow falls on the Moon, which is visible from anywhere on Earth where the Moon is above the horizon, this can be half the planet. In contrast, a solar eclipse occurs when the Moon’s small shadow falls on the Earth, covering only a narrow strip. Therefore, lunar eclipses are more widely visible than solar eclipses.
Question 16. How does Earth’s tilt cause seasonal temperature changes? Explain with an example of a season in the Northern Hemisphere.
Answer
Earth’s tilted axis causes seasons by changing how directly sunlight hits the Northern or Southern Hemisphere, as per the notes. In June, the Northern Hemisphere tilts toward the Sun, receiving more intense sunlight, causing warmer summer temperatures. For example, in India, June is hot because the Sun’s rays are more direct, increasing heat and daylight hours.
Long Answer Questions
Question 1. Explain in detail how the Earth's revolution and tilt cause the seasons. Use examples from both hemispheres.
Answer
The Earth revolves around the Sun in about 365 days. Its axis is tilted at about 23.5°. Due to this tilt:
- In June, the Northern Hemisphere tilts towards the Sun, receiving more direct sunlight and longer days. Hence, it is summer in the Northern Hemisphere and winter in the Southern Hemisphere.
- In December, the situation reverses: the Northern Hemisphere tilts away, getting less sunlight and shorter days, leading to winter, while the Southern Hemisphere gets summer.
This variation in sunlight intensity and duration causes seasonal changes in temperature and weather. For example, in June, India experiences summer, while Australia experiences winter.
Question 2. What is the geometry behind a solar eclipse? Explain how it occurs.
Answer
A solar eclipse occurs when the Moon comes between the Sun and the Earth, blocking the Sun’s light from reaching the Earth. The Moon casts a shadow on Earth, which can either be a total or partial eclipse, depending on the alignment of the Sun, Moon, and Earth. In a total solar eclipse, the Moon completely covers the Sun, and the sky becomes dark during the day. A partial solar eclipse occurs when only a part of the Sun is blocked. This event is brief, as the Moon’s shadow moves across the Earth’s surface due to the Earth's rotation.
Question 3. Explain the process of Earth’s rotation and how it affects the day-night cycle.
Answer
The Earth rotates on its axis, which is an imaginary line running from the North Pole to the South Pole. This rotation occurs in an anti-clockwise direction when viewed from above the North Pole. As the Earth rotates, different parts of the planet move into sunlight, experiencing daytime, while the opposite side is in darkness, experiencing night. This rotation is the primary cause of the cycle of day and night, with each full rotation taking approximately 24 hours.
Question 4. How do the Earth’s rotation and revolution contribute to the changing seasons?
Answer
The Earth’s rotation gives rise to the day-night cycle, but it is the revolution that causes the changing seasons. Due to the Earth’s axial tilt, different hemispheres receive varying amounts of sunlight throughout the year. When the Northern Hemisphere is tilted towards the Sun, it experiences summer, while the Southern Hemisphere experiences winter. In December, the tilt reverses, and the Northern Hemisphere experiences winter, while the Southern Hemisphere experiences summer. This axial tilt and Earth’s orbit around the Sun are the main factors contributing to the seasonal changes.
Question 5. Compare and contrast solar and lunar eclipses in terms of cause, types, appearance, and viewing safety.
Answer
|
Solar Eclipse |
Lunar Eclipse |
|
1. Cause: Moon comes between Earth and Sun, blocking sunlight. |
1. Cause: Lunar eclipse: Earth comes between Sun and Moon, casting a shadow on the Moon. |
|
2. Types: Solar Eclipse are basically of two types, Total and Partial |
2. Types: Lunar eclipse are basically of two types, Total and Partial |
|
3. Appearance: Sun appears fully or partially blocked. In total eclipse, a ‘diamond ring’ may be seen. |
3. Appearance: Moon appears red in total eclipse (blood moon); partially dark in partial eclipse. |
|
4. Visibility: Solar eclipses are visible from a small area for a few minutes. |
4. Visibility: Lunar eclipses are visible from half the Earth and last longer. |
|
5. Viewing Safety: Requires solar filters or indirect methods. Never view directly with naked eyes. |
5. Viewing Safety: Completely safe to view with naked eyes. |
 |
| Solar Eclipse |
 |
| Lunar Eclipse |
Question 6. Describe the difference between Earth’s rotation and revolution.
Answer
Earth’s rotation refers to its spinning on its axis, taking about 24 hours to complete one rotation. This causes day and night. On the other hand, Earth's revolution is the motion of the Earth around the Sun, taking approximately 365 days and 6 hours to complete one full orbit. The revolution is responsible for the changing seasons on Earth.
Question 7. Discuss the safety precautions that should be followed while observing a solar eclipse.
Answer
It is crucial not to look directly at a solar eclipse with the naked eye, as it can cause serious eye damage. Special eclipse glasses that meet safety standards should be used for direct viewing. Alternatively, indirect methods, such as using a mirror to project the Sun’s image onto a screen, can also be used. Never observe a solar eclipse through regular sunglasses, binoculars, or telescopes unless they are equipped with proper solar filters. It is also recommended to participate in organized eclipse viewing events where experts provide the necessary equipment and safety instructions.
Question 8. If the Earth stopped rotating, how would it affect life on Earth in terms of day-night cycle and climate?
Answer
If the Earth stopped rotating, one side would continuously face the Sun, experiencing constant daylight and extreme heat, while the other would remain in perpetual darkness, leading to freezing temperatures. The regular 24-hour cycle of day and night would vanish, disrupting sleep patterns, plant photosynthesis, and animal behaviours. Over time, such imbalance could make large parts of Earth uninhabitable due to extreme climate differences.
Question 9. How would seasons be different if the Earth’s axis were not tilted?
Answer
Without the 23.5° tilt, the Earth would not experience seasons as we know them. All places on Earth would receive nearly equal sunlight throughout the year, resulting in no major temperature variations. Areas near the equator would remain warm, while polar regions would stay cold, but the dramatic shifts of summer and winter would disappear. This would affect ecosystems, agriculture, and migration patterns of animals and birds that depend on seasonal changes.
