๐ฌ Chapter 12 โ Earth, Moon, and the Sun
Class 7 Science | Curiosity | EduGrown Notes
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๐ Earth, Moon, and the Sun โ Day, Night, Seasons and Tides!
๐ Rotation of the Earth โ Day & Night
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๐Rotation = spinning of Earth on its own axis (imaginary line through North and South Poles)
๐Earth rotates West to East (anti-clockwise when viewed from above North Pole)
โฑ๏ธOne complete rotation = 24 hours (one day)
โ๏ธThis rotation causes day and night โ the side facing Sun = day; opposite side = night
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Sun appears to rise in East and set in West โ but actually Earth is rotating, not the Sun moving!
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๐ Earth rotates on its axis โ West to East โ causing day and night!
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โ๏ธ Sun appears to move but Earth is the one rotating!
๐ Revolution of the Earth โ Seasons
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๐Revolution = Earth's movement around the Sun in its orbit
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One complete revolution = 365 days 6 hours โ one year
๐Earth is tilted at 23.5ยฐ on its axis โ this tilt causes the seasons!
โ๏ธWhen Northern Hemisphere tilts toward Sun โ summer in India | Away from Sun โ winter
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๐ Earth orbits the Sun โ one revolution = one year!
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Earth's tilt causes different seasons throughout the year
| Season | Earth's Position | In India |
|---|---|---|
| โ๏ธ Summer | Northern Hemisphere tilted toward Sun | MarchโJune (hot!) |
| โ๏ธ Winter | Northern Hemisphere tilted away from Sun | DecemberโFebruary (cold!) |
| ๐ธ Spring | Earth at mid position | FebruaryโApril |
| ๐ Autumn | Earth at other mid position | SeptemberโNovember |
๐ The Moon โ Earth's Natural Satellite
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๐The Moon is Earth's only natural satellite โ it revolves around Earth
๐Moon takes ~27.3 days to complete one revolution around Earth
๐Moon is non-luminous โ it only reflects sunlight, producing "moonlight"
๐Lunar phases = different shapes of Moon we see as it revolves around Earth (new moon, crescent, full moon)
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๐ Moon phases โ New Moon to Full Moon and back!
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๐ Moon orbits Earth โ Earth orbits Sun!
๐ก Key Differences to Remember!
๐ Rotation (spinning on axis) = causes Day & Night | 24 hours
๐ Revolution (orbiting Sun) = causes Seasons | 365 days
๐ Moon's revolution around Earth = causes Lunar phases | 27.3 days
Earth's tilt (23.5ยฐ) = reason why we have different seasons!
๐ Revolution (orbiting Sun) = causes Seasons | 365 days
๐ Moon's revolution around Earth = causes Lunar phases | 27.3 days
Earth's tilt (23.5ยฐ) = reason why we have different seasons!
๐ Our Solar System โ Quick Facts
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โ๏ธThe Sun is a star โ the centre of our solar system. Its gravity keeps all planets in orbit!
๐Earth is the 3rd planet from the Sun โ the only known planet with life!
๐Earth-Sun distance: ~150 million km | Light from Sun takes ~8 minutes to reach Earth
๐Earth-Moon distance: ~384,000 km | Moon's gravity causes ocean tides!
โญ Quick Summary
โ Top
๐ Key Points
๐Rotation (on axis, WโE, 24 hrs) = Day & Night | Sun rises East, sets West
๐Revolution (around Sun, 365 days) + 23.5ยฐ tilt = Seasons (summer, winter, spring, autumn)
๐Moon = non-luminous satellite of Earth | Revolves in 27.3 days | Causes lunar phases & tides
๐Sun = star (centre) | Earth = 3rd planet | 150 million km away | Sunlight takes 8 mins!