๐ Class 7 Science Curiosity – Chapter 12 Notes
๐ Earth, Moon, and the Sun | Amresh Academy
๐ 1. Introduction
๐ We observe that shadows change length during the day ๐ด
๐ง Reason:
- Not Sun moving ❌
- Earth rotates on its axis ✔️
๐ 2. Rotation of the Earth
๐ Definition:
๐ Rotation = spinning of Earth on its axis
๐ Key Points:
- Axis passes through:
- North Pole ❄️
- South Pole ❄️
- Direction:๐ West → East (anticlockwise)
- Time:๐ 1 rotation = 24 hours ⏳
๐ก 3. Understanding Rotation (Activity)
๐ Merry-go-round example:
- When you rotate → objects seem to move opposite ๐
- Same happens with Earth
๐๐ 4. Day and Night
๐ Cause:
๐ Earth’s rotation
๐ Explanation:
- Half Earth → Day ☀️
- Other half → Night ๐
๐
Sunrise & Sunset:
- Sun rises in East ๐
- Sets in West ๐
๐ 5. Globe Activity
๐ Use globe + torch ๐ฆ
Observation:
- Light side → Day
- Dark side → Night
๐ฎ๐ณ 6. Sunrise in India
๐ Sunrise happens first in eastern India
☀️ 7. Apparent Motion of Sun
๐ Sun appears to:
- Rise in East
- Move across sky
- Set in West
๐งญ 8. Demonstration of Earth’s Rotation
๐ Foucault Pendulum
๐ Demonstrates Earth’s rotation
๐จ๐ฌ Scientist: Leon Foucault
๐ Example: Installed in New Parliament, Delhi
⭐ 9. Apparent Motion of Stars
๐ Stars appear to move ๐
Example:
- Big Dipper (Saptarishi)
- Pole Star (Dhruva Tara)
⭐ Pole Star:
๐ Appears fixed
๐ Moon:
๐ Also appears to rise East & set West
๐ 10. Star Trails
๐ท Long-exposure photos show:
๐ Stars as circular arcs
๐ Called: Star Trails
๐ฎ๐ณ 11. Ancient Indian Astronomy
๐จ๐ฌ Aryabhata
- Explained star movement
- Said Earth rotates
☀️ 12. Revolution of the Earth
๐ Definition:
๐ Movement around Sun
๐ Key Points:
- Path = Orbit ๐
- Shape = Nearly circular
⏳ Time:
๐ 365 days + 6 hours = 1 year
๐ 13. Changing Night Sky
๐ Stars change over months
๐ Used by tribes (Bhil, Pawara) to predict monsoon ๐ง️
๐ฆ️ 14–15. Seasons on Earth
๐ Causes:
- Tilt of Earth’s axis
- Shape of Earth
๐ 16–17. Summer (Northern Hemisphere)
๐ Around June
- Tilted toward Sun
- More heat ๐ฅ
- Longer days
❄️ 18. Winter (Northern Hemisphere)
๐ Around December
- Tilted away from Sun
- Less heat
- Shorter days
๐ 19. Southern Hemisphere
๐ Opposite seasons:
- June → Winter
- December → Summer
๐ 20. Solstices
- ๐ Summer Solstice → 21 June (longest day)
- ❄️ Winter Solstice → 22 Dec (shortest day)
⚖️ 21. Equinox
๐ Day = Night (12 hours)
- ๐ธ Spring → 21 March
- ๐ Autumn → 23 September
๐ง 22. Poles Situation
- Sun visible for 6 months ☀️
- Darkness for 6 months ๐
๐ 23. Equator
๐ Day & night almost equal
๐ No extreme seasons
๐ 24–25. Eclipses
๐ Solar Eclipse
๐ Sun → Moon → Earth
- Moon blocks sunlight
Types:
- Total eclipse
- Partial eclipse
๐ 26. Diamond Ring Effect
๐ Bright ring seen during eclipse ๐
⚠️ 27. Safety
๐ Never look directly at Sun
✔️ Use:
- Special glasses
- Projection method
๐ง 28. Superstitions
๐ 29. Lunar Eclipse
๐ Sun → Earth → Moon
Types:
- Total (red moon) ๐ด
- Partial
๐ Safe to watch ✔️
๐ญ 30. Astronomy in India
๐ Kodaikanal Solar Observatory (Tamil Nadu)
๐ Studies Sun
๐จ๐ฌ 31. Indian Scientist
๐ M. K. Vainu Bappu
- Father of Modern Indian Astronomy
- Built observatories in India
๐ 32. Final Summary
✨ Perfect for revision + exams + teaching ๐
