Our Earth and Sky
1. The Sun
The SUN is a big, bright STAR at the centre of our solar system.
'The Sun gives us LIGHT and HEAT. Without the Sun, Earth would be a DARK and FROZEN place — nothing could live!'
Key Facts about the Sun:
| Fact | Detail |
|---|---|
| What is it? | A STAR — a huge ball of hot, glowing gas |
| Distance from Earth | About 150 million km |
| Temperature | About 5,500°C (surface) |
| Size | About 109 times WIDER than Earth |
| Colour | Actually WHITE (looks yellow because of Earth's atmosphere) |
Importance of the Sun:
- Gives us LIGHT to see during the day.
- Gives us HEAT to keep us warm.
- Helps plants make FOOD (photosynthesis).
- Dries our clothes after washing.
- Drives the WATER CYCLE.
'NEVER look DIRECTLY at the Sun — it can DAMAGE your eyes permanently!'
2. The Moon
The MOON is Earth's NEAREST neighbour in space.
'The Moon is a NATURAL SATELLITE — it goes around (orbits) the Earth.'
Key Facts about the Moon:
| Fact | Detail |
|---|---|
| What is it? | Earth's ONLY natural satellite |
| Distance from Earth | About 3,84,400 km |
| Size | About 1/4 of Earth's width |
| Light | Does NOT make its own light — REFLECTS sunlight |
| Temperature | 127°C (day) to -173°C (night) |
| Atmosphere | NONE — no air, no wind, no sound |
| Water | NONE on the surface |
The Moon's Shape:
The Moon CHANGES shape in the sky over a month. These are called PHASES.
- New Moon: We cannot see the Moon.
- Crescent Moon: A thin SLIVER.
- Half Moon: HALF of the Moon is lit.
- Full Moon: The ENTIRE Moon is bright!
'Did you know? The Moon looks BIG when it is near the horizon — but this is an OPTICAL ILLUSION. It is the same size as when it is high in the sky!'
3. Stars
STARS are HUGE, glowing balls of gas — just like the Sun!
'Stars look tiny because they are VERY far away. The Sun is the CLOSEST star to Earth.'
Key Facts about Stars:
- They TWINKLE at night.
- They are SUNS in other parts of the universe.
- Some stars are BIGGER than the Sun!
- We can see them only at NIGHT because sunlight is too bright during the day.
Constellations:
A CONSTELLATION is a group of stars that forms a PATTERN in the sky.
| Constellation | Looks Like | Where to See |
|---|---|---|
| Big Dipper (Saptarishi) | A LADLE or scoop | Northern sky — all year |
| Orion | A HUNTER with a belt of three stars | Winter sky |
| Cassiopeia | A W shape | Northern sky |
4. Day and Night
DAY and NIGHT happen because Earth SPINS on its axis.
'Earth is like a TOP — it spins around and around. One full spin takes 24 HOURS.'
How It Works:
- The side of Earth FACING the Sun has DAY.
- The side AWAY from the Sun has NIGHT.
- As Earth spins, places move from day → night → day again.
'When India has DAY, America has NIGHT. When you are sleeping, children in America are playing!'
5. Seasons
SEASONS are caused by Earth's TILT and its movement around the Sun.
'India has THREE main seasons: Summer, Rainy (Monsoon), and Winter.'
| Season | Months | Weather |
|---|---|---|
| Summer | March to May | HOT — sun is high in the sky |
| Monsoon (Rainy) | June to September | WET — lots of rain |
| Winter | October to February | COLD — sun is low in the sky |
What We Do in Different Seasons:
- Summer: Wear COTTON clothes. Drink cold water. Eat mangoes and watermelons.
- Monsoon: Carry an UMBRELLA. Wear raincoats. See RAINBOWS!
- Winter: Wear WOOLLEN clothes. Drink hot soup. Sit in the sun.
6. Earth's Surface
Earth's surface has TWO main features — LAND and WATER.
Land:
About 29% of Earth's surface is LAND.
| Landform | Description | Example |
|---|---|---|
| Mountains | Very HIGH land | Himalayas |
| Hills | Medium-height land | Nilgiri Hills |
| Plains | Flat land | Northern Plains |
| Plateaus | Flat land HIGH above surroundings | Deccan Plateau |
| Valleys | Low land BETWEEN mountains | Kashmir Valley |
| Deserts | VERY dry, sandy land | Thar Desert |
Water:
About 71% of Earth's surface is WATER.
| Water Body | Description | Example |
|---|---|---|
| Ocean | LARGEST water body | Indian Ocean |
| Sea | Smaller than an ocean | Arabian Sea |
| River | Flowing water | River Ganga |
| Lake | Water surrounded by land | Dal Lake |
| Pond | Small lake | Village pond |
7. Common Mistakes
- Thinking the Moon makes its own light: 'The Moon does NOT make light. It REFLECTS the Sun's light — like a giant mirror in the sky!'
- Believing the Sun moves around the Earth: 'The Earth moves around the SUN, not the other way around. The Sun APPEARS to move because Earth is spinning.'
- Thinking stars are tiny: 'Stars are HUGE — they are suns billions of kilometres away. They just look tiny because of the distance.'
- Confusing weather and seasons: 'Weather changes DAILY (today is sunny, tomorrow rainy). Seasons change EVERY FEW MONTHS (summer to monsoon to winter).'
8. Key Facts to Remember
- 'The SUN is a star that gives us light and heat.'
- 'The MOON reflects sunlight and orbits Earth.'
- 'STARS are huge, distant suns that twinkle at night.'
- 'DAY and NIGHT happen because Earth ROTATES (spins).'
- 'SEASONS change because of Earth's TILT and revolution.'
- 'Earth's surface is 29% LAND and 71% WATER.'
- 'NEVER look directly at the Sun!'
9. Self-Test
Q1: What is the Sun? Why is it important for life on Earth?
Q2: Does the Moon make its own light? Explain.
Q3: Why does the Sun look bigger than other stars?
Q4: Why do we have day and night on Earth?
Q5: Name the three main seasons in India.
Q6: What is Earth's surface made of? How much is water?
Q7: What is a constellation? Name one.
Q8: What should you wear in summer? What should you wear in winter?
Answers:
A1: The Sun is a STAR — a huge ball of hot, glowing gas. It gives us LIGHT and HEAT, which are essential for all life on Earth. A2: NO. The Moon REFLECTS the Sun's light. It does not produce any light of its own. A3: Because the Sun is the CLOSEST star to Earth. Other stars are very far away. A4: Earth SPINS on its axis. The side facing the Sun has DAY. The side away from the Sun has NIGHT. A5: Summer (March-May), Monsoon (June-September), Winter (October-February). A6: 29% LAND and 71% WATER. A7: A constellation is a group of stars that form a pattern in the sky. Example: Big Dipper (Saptarishi) or Orion. A8: Summer — LIGHT COTTON clothes. Winter — WOOLLEN clothes (sweaters, jackets).
