Chapter 10: Our Sky
Chapter at a Glance
The sky looks different at different times of the day. In the morning it is orange and the Sun looks orange too, in the afternoon the sunlight is strong, and at night we see the Moon and stars. Birds, animals, plants and people also change what they do from morning to night. The Sun is the brightest object in the sky. It is so bright that we cannot see other stars during the day, and it gives us light and heat. The Sun seems to rise in the East, climb overhead by noon, and set in the West.
Shadows change during the day as well. They are long in the morning, short at noon, and long again in the evening, but the evening shadow falls in the opposite direction. A torch-and-stick activity shows that a shadow gets bigger when the object is closer to the light, and that the shadow’s direction changes when the light’s direction changes. Because the Sun appears to move from East to West, our shadows move too. Long ago, people used shadows to tell time with a sundial. Raja Jai Singh built the Jantar Mantar observatories, whose Samrat Yantra is a huge sundial. Shadow puppetry is an old art form in India.
At night the sky is full of twinkling stars that form patterns. The Moon is the biggest object in the night sky, and its shape seems to change from night to night. A full, round Moon is Poornima, and a night with no Moon is Amavasya. Ancient people counted days using the Moon’s shapes, which led to the first calendars. Many festivals depend on the Moon, such as Diwali on Amavasya, Raksha Bandhan and Guru Poornima on full-Moon days, and Eid after the new Moon. On 23 August 2023, India’s Vikram Lander of the Chandrayaan mission landed successfully on the Moon.
Word Meanings
| Word | Simple Meaning |
|---|---|
| Sky | The space above the Earth that we see when we look up |
| Sunrise | The time when the Sun appears in the morning |
| Sunset | The time when the Sun goes down in the evening |
| Overhead | Directly above our head |
| Shadow | A dark shape formed when an object blocks light |
| Source of light | Something that gives out light, like the Sun or a torch |
| Sundial | A device that tells time using the shadow of the Sun |
| Jantar Mantar | Old observatories built by Raja Jai Singh to study the sky |
| Samrat Yantra | A giant sundial at Jantar Mantar |
| Shadow puppetry | A show where puppets’ shadows tell a story on a screen |
| Twinkle | To shine with a flickering light |
| Pattern | Shapes that repeat or form a design |
| Poornima | Full Moon night, when the Moon looks completely round |
| Amavasya | New Moon night, when the Moon is not seen |
| Calendar | A chart showing days, weeks and months |
| Lander | A spacecraft that lands on the surface of the Moon or a planet |
| Chandrayaan | India’s mission to explore the Moon |
Important Topics
1. The Sky at Different Times
| Morning sky | Afternoon sky | Night sky |
|---|---|---|
| Orange-coloured sky | Bright blue sky | Dark sky |
| Orange, rising Sun | Strong sunlight | Moon and stars |
| Birds chirp and fly out | Animals rest in shade | Owls and bats come out |
| People wake up and get ready | People work and study | People rest and sleep |
2. The Sun
- The brightest object in the sky; gives us light and heat.
- Other stars cannot be seen in the day because the Sun is so bright.
- It appears to rise in the East, come overhead at noon and set in the West.
3. Shadows During the Day
| Time | Shadow length | Direction |
|---|---|---|
| Morning | Long | Towards the West (Sun in the East) |
| Noon | Shortest | Almost under the object (Sun overhead) |
| Evening | Long | Towards the East (Sun in the West) |
4. Torch and Stick Activity
- The closer the object is to the light, the bigger its shadow.
- When the direction of the light changes, the direction of the shadow also changes.
- A shadow always forms on the side opposite to the light.
5. Telling Time with Shadows
- A sundial tells time by the Sun’s shadow.
- Raja Jai Singh built Jantar Mantar in Jaipur, Ujjain, Delhi, Varanasi and Mathura.
- The Samrat Yantra at Jantar Mantar is a sundial that tells time accurately.
6. The Night Sky and the Moon
- Stars form patterns in the night sky (like the Saptarshi).
- The Moon is the biggest object in the night sky, and its shape seems to change.
- Poornima (full Moon): completely round. Amavasya (new Moon): not visible.
- In between, the Moon looks like the letter ‘C’ or like a half circle.
- Ancient people counted days using the Moon’s shapes, which gave rise to the earliest calendars.
7. Festivals Linked to the Sun and Moon
| Festival | Linked with |
|---|---|
| Diwali | Amavasya (no Moon) |
| Raksha Bandhan, Guru Poornima, Buddha Poornima | Full Moon |
| Eid | First sighting of the Moon after the new Moon |
| Karva Chauth | Moonrise |
| Chhath Puja, Pongal, Makar Sankranti | The Sun |
8. Chandrayaan Mission
- On 23 August 2023, India’s Vikram Lander landed safely on the Moon and collected data about its surface.
Question-Answers
Very Short Answer Questions
- What is the brightest object in the sky? The Sun.
- What does the Sun give us? Light and heat.
- In which direction does the Sun rise? East.
- In which direction does the Sun set? West.
- When is our shadow the shortest? At noon.
- What is a sundial? A device that tells time using shadows.
- Who built Jantar Mantar? Raja Jai Singh of Jaipur.
- What is the sundial at Jantar Mantar called? Samrat Yantra.
- Which is the biggest object in the night sky? The Moon.
- What is the full Moon night called? Poornima.
- What is the no-Moon night called? Amavasya.
- On which night is Diwali celebrated? Amavasya (no Moon).
- When did Vikram Lander land on the Moon? 23 August 2023.
Short Answer Questions
Q1. Why can we not see stars during the day?
The Sun is so bright during the day that its light hides the fainter light of other stars.
Q2. How does the Sun appear to move across the sky?
The Sun appears to rise in the East in the morning, come overhead at noon, and slowly move down to set in the West in the evening.
Q3. How does a shadow change when an object moves closer to the light?
When an object is closer to the source of light, its shadow becomes bigger. When it moves away, the shadow becomes smaller.
Q4. How did the Moon help ancient people?
Ancient people noticed that the Moon’s shape changes in a regular pattern. They used these changes to count days, which led to the first calendars.
Q5. Name festivals celebrated on a full Moon and on a new Moon.
Raksha Bandhan, Guru Poornima and Buddha Poornima are celebrated on a full Moon. Diwali is celebrated on a new Moon (Amavasya).
Long Answer Questions
Q1. Explain how shadows change from morning to evening, and why.
In the morning the Sun is low in the East, so shadows are long and fall towards the West. At noon the Sun is almost overhead, so shadows are the shortest. In the evening the Sun is low in the West, so shadows become long again but fall towards the East. The shadows change because the Sun appears to move across the sky from East to West, and a shadow always falls on the side opposite the light.
Q2. Describe the torch-and-stick activity and what we learn from it.
Close the doors and windows to make the room dark. Hold a stick and shine a torch on it. Move the stick closer to and farther from the torch, then change the direction of the torch. We learn that the shadow becomes bigger when the stick is closer to the light, and that the shadow’s direction changes when the light’s direction changes.
Q3. Describe the changing shapes of the Moon and their importance in our lives.
The Moon looks different on different nights. On Poornima it is a full round circle. On some nights it looks like the letter ‘C’ or like a half circle. On Amavasya it is not visible at all. This pattern repeats regularly, so ancient people used it to count days and make calendars. Many of our festivals, like Diwali, Raksha Bandhan, Eid and Karva Chauth, are still decided by the Moon.
Textbook Exercise Answers
Q1. Give two differences between:
| Pair | First | Second |
|---|---|---|
| (a) Day and night | Day: the Sun is out, it is bright and warm | Night: the Moon and stars are out, it is dark and cooler |
| (b) Morning sky and evening sky | Morning: the Sun rises in the East, shadows point West | Evening: the Sun sets in the West, shadows point East |
| (c) Our activities in the day and at night | Day: we go to school, study, work and play | Night: we have dinner, rest and sleep |
| (d) Animals in the day and at night | Day: sparrows, crows and cows are active | Night: owls, bats and crickets are active |
Q2. Two questions Meera can ask.
(a) Does the Sun really move, or does it only seem to move?
(b) Why does the Sun always rise in the East and set in the West?
Q3. Figure it out.
In the morning the Sun is in the East, so my shadow points West. In the afternoon the Sun is in the West, so my shadow points East. The shadow changes direction because the Sun appears to move across the sky. The length will not be the same at all times: it is longer when the Sun is low and shorter when it is high. If both times are equally far from noon, the lengths will be about the same.
Q4. Get creative with words.
(a) Sample poem:
Blue by day and gold at dawn,
The Sun wakes up and night is gone.
When evening comes, the stars peep through,
The silver Moon says ‘hello’ to you!
(b) Riddle answer: Shadow.
Other in-text questions
- When the Sun rises: the sky turns orange, birds chirp and fly out, and people wake up and start their work.
- When the Sun sets: the sky turns orange-red, birds return to their nests, and lights are switched on at home.
- Are shadows formed only in sunlight? No. Shadows form with any light, such as a torch, bulb or candle.
- Is there a pattern to the Moon’s changing shape? Yes. It grows from no Moon to full Moon and back again, repeating about every month.