Class 7 : Science – ( English ) : Lesson 12. Earth, Moon, and the Sun
EXPLANATION AND ANALYSIS
🧭 The Earth, Moon, and the Sun form a closely connected system that shapes life and time on our planet.
Day and night 🌞🌙, months 📅, seasons 🍂🌸, and tides 🌊 are all linked to their movements.
🧠 Understanding this system helps us explain natural cycles and observe the universe logically.
🔍 Studying these heavenly bodies builds curiosity about space and our place in it 🌌.
🌍 The Earth is our home planet.
It supports life because it has air 🌬️, water 💧, suitable temperature 🌡️, and gravity ⚖️.
🧠 Earth has two important motions.
Rotation 🔄 on its axis
Revolution 🧭 around the Sun
🧠 These motions cause day–night and seasons.
🌞 Rotation of the Earth takes place from west to east.
One complete rotation causes day and night.
🌅 When a region faces the Sun, it is day.
🌃 When it turns away, it is night.
🧠 Rotation takes nearly one day and affects temperature and daily life.
🌞 The Sun is a star at the center of the solar system.
It provides light ✨ and heat 🔥.
🧠 The Sun is the main source of energy for Earth.
Plants use sunlight for photosynthesis 🌱☀️.
Animals depend on plants for food 🐄.
🌍 Without the Sun, life on Earth would not exist.
🧭 Revolution of the Earth occurs along a fixed path called an orbit 🧭.
One revolution around the Sun takes one year 📅.
🧠 Revolution, along with Earth’s tilted axis 📐, causes seasons.
🍂 Seasons change because Earth’s axis is tilted.
Different parts receive different amounts of sunlight.
🧠 Summer ☀️ occurs when a region receives more sunlight.
Winter ❄️ occurs when it receives less.
🌸 Spring and autumn are transition seasons.
🌕 The Moon is Earth’s natural satellite.
It does not produce its own light ✖️.
It reflects sunlight ✨.
🧠 The Moon revolves around the Earth and also rotates on its axis.
🌙 Phases of the Moon occur due to its changing position.
New Moon 🌑
Full Moon 🌕
Crescent 🌒
Half Moon 🌓
🧠 One complete set of phases forms a month.
🌊 The Moon’s gravity causes tides in oceans.
Water rises and falls regularly.
🧠 Tides affect fishing 🎣, ports ⚓, and coastal life.
🧭 The Moon also helps stabilize Earth’s rotation.
It influences climate balance 🌍.
🧠 This shows the importance of the Earth–Moon relationship.
🌌 The Sun, Earth, and Moon always move in space.
Their movements are predictable and regular.
🧠 This predictability helps in calendars 📆, navigation 🧭, and science.
🧠 Observing the sky developed early astronomy.
People tracked stars 🌟 and planets 🪐.
🧠 Scientific tools improved observation accuracy 🔭.
🌍 Understanding space encourages respect for Earth.
It highlights Earth’s uniqueness 🌱.
🧠 This knowledge supports environmental responsibility.
🧭 Studying Earth, Moon, and Sun builds scientific thinking.
Observation 👀
Reasoning 🧠
Pattern recognition 🧩
🧠 It connects science with daily experience.
📜 The Earth–Moon–Sun system explains time, seasons, and natural rhythms.
It shows how cosmic movements affect life.
🚀 Learning about space inspires curiosity and exploration.
📝 Summary of the Lesson
The Earth, Moon, and the Sun form a system that controls many natural events. Earth rotates on its axis to produce day and night and revolves around the Sun to produce seasons. The Sun provides heat and light and supports all life on Earth. The Moon is Earth’s natural satellite and reflects sunlight. Its changing positions cause different phases of the Moon and influence ocean tides. The tilted axis of Earth and its revolution around the Sun cause seasonal changes. Understanding these movements helps explain time, climate, and natural cycles.
⚡ Quick Recap
⭐ Earth supports life
⭐ Rotation causes day and night
⭐ Revolution causes seasons
⭐ Sun provides energy
⭐ Moon reflects sunlight
⭐ Moon causes tides
⭐ Space movements shape life
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TEXTBOOK QUESTIONS
🔒 ❓ 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:
🔹 During one complete rotation of the Earth (24 hours):
North Pole receives 24 hours of sunlight (continuous day)
South Pole receives 24 hours of darkness at the same time
🔹 This happens because Earth’s axis is tilted, causing polar day and polar night
🔒 ❓ Question 2
Fill in the blanks:
📌 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.
🔒 ❓ Question 3
State whether the following statements are True (T) or False (F):
📌 Answer:
(i) Lunar eclipse occurs when the Sun comes between the Earth and the Moon. → False
(ii) Sunrise happens earlier in Gujarat than in Jharkhand. → False
(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
(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
🔒 ❓ Question 4
Padmashree saw the Orion constellation nearly overhead at 8 pm yesterday. When will she see Orion overhead today?
📌 Answer:
🔹 She will see Orion overhead about 4 minutes earlier today
🔹 This is because Earth moves slightly in its orbit each day
🔹 Stars appear to rise 4 minutes earlier daily
✔️ Approximate time today: 7:56 pm
🔒 ❓ Question 5
Nandhini saw a group of stars rising at midnight on 21 June. When will she see the same group rising at midnight next year?
📌 Answer:
🔹 She will see the same group of stars rising at midnight again on 21 June next year
🔹 This happens because Earth completes one revolution around the Sun in one year
🔒 ❓ Question 6
Abhay noticed that when it was daytime in India, his uncle in the USA was sleeping. What is the reason?
📌 Answer:
🔹 Earth rotates from west to east
🔹 Different parts of Earth face the Sun at different times
🔹 India and the USA lie in different longitudes
🔹 Hence, when it is day in India, it is night in the USA
🔒 ❓ Question 7
Four friends used different ways to see the solar eclipse. Who was careless?
📌 Answer:
✔️ Careless person: Adithya
🔹 He looked directly at the Sun with naked eyes
🔹 This can damage the eyes permanently
🔹 Other methods are safe:
Solar eclipse goggles
Projection using mirror
Planetarium observation
🔒 ❓ Question 8
Fill in the circles in Fig. 12.18 appropriately with Sun, Moon, Earth.
📌 Answer:
🔹 Solar eclipse (left to right):
Sun – Moon – Earth
🔹 Lunar eclipse (left to right):
Sun – Earth – Moon
🔒 ❓ Question 9
The Moon is much smaller than the Sun, yet it can block the Sun completely during a total solar eclipse. Why?
📌 Answer:
🔹 The Moon is much closer to the Earth than the Sun
🔹 Because of this, the Moon appears almost equal in size to the Sun in the sky
🔹 Hence, it can completely cover the Sun during a total solar eclipse
🔒 ❓ Question 10
Indian cricket team matches in Australia are often held in December. Should they pack winter or summer clothes?
📌 Answer:
✔️ They should pack summer clothes
🔹 Australia lies in the Southern Hemisphere
🔹 Seasons there are opposite to India
🔹 December is summer in Australia
🔒 ❓ Question 11
Why can lunar eclipses be seen from a large part of the Earth, but total solar eclipses only from a small part?
📌 Answer:
🔹 During a lunar eclipse, Earth’s shadow falls on the Moon
🔹 This shadow is very large
🔹 Hence, the lunar eclipse is visible from many places on Earth
🔹 During a solar eclipse, the Moon’s shadow on Earth is very small
🔹 Therefore, a total solar eclipse is visible only from a limited area
🔒 ❓ Question 12
If the Earth’s axis were not tilted, what would be the effect on seasons?
📌 Answer:
🔹 There would be no seasons
🔹 All places would receive nearly equal sunlight throughout the year
🔹 Days and nights would be of equal length everywhere
🔹 Seasonal changes like summer and winter would not occur.
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OTHER IMPORTANT QUESTIONS
SECTION 1 — MCQs (5 Questions)
🔒 ❓ Q1. Which movement of the Earth causes day and night?
🟢 1️⃣ Revolution
🔵 2️⃣ Rotation
🟡 3️⃣ Oscillation
🟣 4️⃣ Translation
✔️ Answer: 🔵 2️⃣ Rotation
🔒 ❓ Q2. Which celestial body is the nearest star to the Earth?
🟢 1️⃣ Moon
🔵 2️⃣ Sun
🟡 3️⃣ Mars
🟣 4️⃣ Venus
✔️ Answer: 🔵 2️⃣ Sun
🔒 ❓ Q3. What is the time taken by the Earth to complete one revolution around the Sun?
🟢 1️⃣ 24 hours
🔵 2️⃣ 30 days
🟡 3️⃣ 365 days
🟣 4️⃣ 12 hours
✔️ Answer: 🟡 3️⃣ 365 days
🔒 ❓ Q4. Which phase of the Moon occurs when it is completely dark?
🟢 1️⃣ Full Moon
🔵 2️⃣ Half Moon
🟡 3️⃣ New Moon
🟣 4️⃣ Crescent Moon
✔️ Answer: 🟡 3️⃣ New Moon
🔒 ❓ Q5. Which phenomenon occurs due to the shadow of the Earth on the Moon?
🟢 1️⃣ Solar eclipse
🔵 2️⃣ Lunar eclipse
🟡 3️⃣ Day and night
🟣 4️⃣ Seasons
✔️ Answer: 🔵 2️⃣ Lunar eclipse
SECTION 2 — Very Short Answer (5 Questions)
🔒 ❓ Q6. Name the natural satellite of the Earth.
📌 ✅ Answer: Moon
🔒 ❓ Q7. What do we call the path of the Earth around the Sun?
📌 ✅ Answer: Orbit
🔒 ❓ Q8. Which movement of the Earth causes seasons?
📌 ✅ Answer: Revolution
🔒 ❓ Q9. Name the dark phase of the Moon.
📌 ✅ Answer: New Moon
🔒 ❓ Q10. Which body provides light and heat to the Earth?
📌 ✅ Answer: Sun
SECTION 3 — Short Answer (3 Questions)
🔒 ❓ Q11. Why do we have day and night on the Earth?
📌 ✅ Answer:
🔹 The Earth rotates on its axis.
🔸 The side facing the Sun experiences day.
🔹 The opposite side remains in darkness, causing night.
🔒 ❓ Q12. What causes phases of the Moon?
📌 ✅ Answer:
🔹 The Moon reflects sunlight.
🔸 Its changing position around the Earth alters the visible portion.
🔹 This results in different phases of the Moon.
🔒 ❓ Q13. Why does the Moon not have its own light?
📌 ✅ Answer:
🔹 The Moon is not a star.
🔸 It does not produce light.
🔹 It shines by reflecting sunlight.
SECTION 4 — Long Answer (1 Question)
🔒 ❓ Q14. Explain the movements of the Earth and their effects.
📌 ✅ Answer:
🔹 The Earth shows two movements: rotation and revolution.
🔸 Rotation on its axis causes day and night.
🔹 Revolution around the Sun takes about 365 days.
🔸 Revolution along with Earth’s tilt causes seasons.
🔹 These movements help maintain time cycles and climatic changes on Earth.
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ADVANCE KNOWLEDGE
🌌 A Cosmic Family We Live Inside
Every day we see the Sun rise and set, watch the Moon change its shape, and live on Earth without realizing that we are part of a dynamic cosmic system. Earth, Moon, and Sun are not isolated objects—they are deeply connected partners, bound by gravity, motion, and energy.
🧠 Big idea:
Life on Earth exists because this three-body system is perfectly balanced, not by chance, but by physical laws.
🌍 Earth: A Rarely Balanced Planet
Earth is not just a planet—it is a life-support system.
🧠 Earth’s special features:
Liquid water on the surface
Protective atmosphere
Moderate temperature
Suitable gravity
⭐ Even a small change in Earth’s distance from the Sun would make life impossible.
🧠 Earth is often called the Goldilocks planet—not too hot, not too cold.
🌞 The Sun: Source of All Major Energy
The Sun is a medium-sized star, yet it dominates our solar system.
🌞 The Sun provides:
Light
Heat
Energy for photosynthesis
⭐ More than 99% of the solar system’s mass lies in the Sun.
🧠 Every food chain, weather system, and climate pattern begins with solar energy.
⚠️ Misconception vs Reality
⚠️ Misconception: The Sun moves around the Earth
✅ Reality: Earth revolves around the Sun
⚠️ Misconception: The Sun is on fire
✅ Reality: The Sun produces energy by nuclear reactions, not burning
⚠️ Misconception: The Moon produces its own light
✅ Reality: Moonlight is reflected sunlight
🌕 The Moon: Earth’s Silent Partner
The Moon is Earth’s only natural satellite.
🌕 Key roles of the Moon:
Controls ocean tides
Stabilizes Earth’s tilt
Influences climate stability
⭐ Without the Moon:
Days would be shorter and unstable
Seasons would vary wildly
🧠 The Moon acts like a cosmic stabilizer.
🌗 Phases of the Moon: A Dance of Light
The Moon’s changing shape is an illusion.
🧠 Phases occur due to:
Moon’s revolution around Earth
Changing sunlight angles
⭐ The Moon does not change shape—it only shows different illuminated portions.
🧠 This cycle helped ancient humans create calendars.
🌞 Day and Night: Earth’s Spin
Day and night occur because Earth rotates on its axis.
🌍 One rotation ≈ 24 hours
🧠 The side facing the Sun experiences day; the opposite side experiences night.
⭐ Rotation is so smooth that we do not feel Earth moving at all.
🌦️ Seasons: Tilt Makes the Difference
Seasons are not caused by distance from the Sun.
🧠 True cause:
Earth’s axis is tilted
Different parts receive different sunlight
⭐ When the Northern Hemisphere tilts toward the Sun → summer
⭐ When tilted away → winter
🧠 Tilt creates diversity in climate and ecosystems.
🌍 Eclipses: Shadows in Space
Eclipses are cosmic shadow events.
🌑 Solar eclipse
Moon blocks Sun
Happens during new Moon
🌕 Lunar eclipse
Earth blocks sunlight to Moon
Happens during full Moon
⭐ Eclipses prove that light travels in straight lines.
🌊 Tides: The Moon’s Invisible Pull
Ocean tides are caused by gravitational attraction.
🧠 Moon’s gravity:
Pulls ocean water
Creates high and low tides
⭐ The Sun also affects tides, but the Moon’s closeness makes its effect stronger.
🧠 Tides influence:
Marine life
Coastal ecosystems
Human activities
🌌 Earth–Moon–Sun Beyond Earth
Other planets show similar systems.
🌌 Examples:
Jupiter and its moons
Saturn and ring systems
🧠 Studying our system helps scientists understand planetary systems across the universe.
🚀 Modern Space Science
🚀 Scientists study this system using:
Satellites
Space telescopes
Moon missions
🧠 These studies help:
Predict climate change
Track asteroids
Understand Earth’s future
⭐ Space science protects Earth as much as it explores space.
🌡️ Changing Balance: A Warning
Human activity is altering Earth’s energy balance.
⚠️ Results include:
Rising global temperatures
Melting ice
Changing weather patterns
🧠 The Sun provides energy—but how Earth handles it decides climate.
⭐ Amazing Cosmic Facts
⭐ Sunlight takes about 8 minutes to reach Earth
⭐ The Moon is slowly moving away from Earth
⭐ Earth travels around the Sun at ~30 km per second
⭐ Without gravity, this system would collapse instantly
🧠 Why Curious Minds Must Understand This System
This topic teaches:
Motion
Gravity
Energy transfer
Planetary balance
🧠 It helps students see Earth not as a flat surface, but as a moving world in space.
🌟 Final Thought
Earth, Moon, and Sun are locked in a silent dance—
stable, powerful, and precise.
🧠 Understanding this cosmic partnership teaches us how fragile and precious our home truly is.
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