Summary
Chapter 10 of the Class 4 The World Around Us NCERT textbook (Our Wondrous World), "Our Sky", introduces young learners to the ever-changing sky — how sunlight, shadows, the Moon's phases, and stars shape our days and nights. Students observe shadow patterns at morning, noon, and evening; learn about sundials and Jantar Mantar; and explore Moon phases linked to Indian festivals. Download the PDF and read a chapter summary and Q&A below.
- The Sun and the Changing Sky — The chapter explains that the sky looks different in the morning, afternoon, and at night. The Sun is the brightest object in the sky — so bright that other stars cannot be seen while it is present. It appears to rise in the East, move overhead by noon, and then move toward the West before disappearing at sunset.
- Shadows and How They Change — Shadows are longest in the early morning and evening, and shortest at noon. The chapter shows through a torch-and-stick activity that a shadow's size depends on how close the object is to the light source, and its direction depends on the direction of the light. Morning and evening shadows fall in opposite directions because the Sun's position in the sky changes.
- Sundials and Jantar Mantar — Ancient people noticed that shadows move predictably with the Sun and invented the sundial to tell time. Raja Jai Singh of Jaipur built Jantar Mantar in five cities — Jaipur, Ujjain, Delhi, Varanasi, and Mathura. Its Samrat Yantra is a large sundial that can accurately tell the time from shadow position.
- The Moon, Stars, and Indian Festivals — At night the sky fills with twinkling stars and the Moon, which appears largest among night-sky objects. The Moon's shape changes across nights — from a full circle (Poornima) to a C-shape to half, to invisible (Amavasya). Ancient cultures used these phases as the earliest calendars. Many Indian festivals — Diwali, Rakshabandhan, Guru Poornima, Eid — are tied to specific Moon phases. India's Vikram Lander landed on the Moon on 23 August 2023 as part of the Chandrayaan mission.
Key points & formulas
- 01The sky changes colour in the morning, afternoon, and at night — from orange at sunrise to blue in daytime to star-filled black at night.
- 02The Sun is the brightest object in the sky and gives us light and heat; its brightness hides other stars during the day.
- 03The Sun appears to move from East to overhead (noon) and then toward the West each day.
- 04Morning and evening shadows are long; noon shadows are the shortest. Evening shadows fall in the opposite direction to morning shadows.
- 05A torch-and-stick activity shows that a shadow gets bigger when the object is closer to the light source, and changes direction when the light source moves.
- 06Raja Jai Singh built Jantar Mantar in Jaipur, Ujjain, Delhi, Varanasi, and Mathura; the Samrat Yantra sundial there tells accurate time using shadows.
- 07The Moon changes shape across nights — full Moon (Poornima), half Moon, crescent (C-shape), and no Moon (Amavasya) — the basis of early calendars.
- 08Indian festivals like Diwali (no Moon), Rakshabandhan and Guru Poornima (full Moon), and Eid (first crescent after new Moon) are linked to Moon phases.
- 09India's Chandrayaan mission Vikram Lander successfully landed on the Moon on 23 August 2023.
Frequently asked questions
01What is Chapter 10 of Class 4 Our Wondrous World about?
Chapter 10, 'Our Sky', is about the sky as observed at different times of day and night. It covers the Sun's apparent movement, how shadows change, the sundial, Moon phases, stars, and Indian festivals connected to the Moon.
02How does the sky look different in the morning, afternoon, and at night?
In the morning the sky appears orange with an orange-coloured Sun. In the afternoon sunlight is strong and the sky is bright. At night the sky is dark and filled with the Moon and thousands of twinkling stars.
03Why are morning and evening shadows long while noon shadows are short?
At morning and evening the Sun is low in the sky, so it casts long shadows. At noon the Sun is almost directly overhead, making shadows very short. This is what the chapter's pictures of early morning, noon, and evening shadows illustrate.
04Why do morning and evening shadows fall in opposite directions?
The chapter explains that the direction of a shadow depends on the position of the light source. In the morning the Sun is in the East, so shadows fall toward the West. In the evening the Sun is in the West, so shadows fall toward the East — the opposite direction.
05What does the torch-and-stick activity in Chapter 10 teach?
The activity shows that if an object is moved closer to the light source the shadow becomes bigger, and if the direction of the light source changes the direction of the shadow also changes. This helps students understand why shadows shift throughout the day as the Sun moves.
06What is a sundial and where is the famous one in India?
A sundial is a device that tells time using the position of a shadow. Raja Jai Singh of Jaipur built Jantar Mantar in five cities — Jaipur, Ujjain, Delhi, Varanasi, and Mathura. The Samrat Yantra at Jantar Mantar is a large sundial that can tell accurate time from shadows.
07What are the different shapes of the Moon mentioned in the chapter?
The chapter describes the Moon as sometimes a complete circle (Poornima or full Moon), sometimes like the letter 'C' (crescent), sometimes half (like it has been cut in the middle), and on some nights not visible at all (Amavasya or new Moon).
08Which Indian festivals are connected to the Moon according to this chapter?
Diwali is celebrated on the night of Amavasya (no Moon). Rakshabandhan, Guru Poornima, and Buddha Poornima are celebrated on Poornima (full Moon). Eid is celebrated on the first night after a new Moon when a crescent first appears. Chhath Puja, Karva Chauth, and Pongal are also mentioned.
09What is Chandrayaan and what did it achieve?
The chapter mentions India's Chandrayaan mission, in which the Vikram Lander successfully landed on the Moon on 23 August 2023 and collected data about the Moon's surface.
10How did ancient people use the Moon to track time?
Ancient cultures observed that the Moon's shape changes in a regular pattern across the month. They used these phases to count the days, which led to the creation of the earliest calendars.
11What is Poornima and what is Amavasya?
Poornima is the full Moon night when the Moon appears as a complete circle. Amavasya is the new Moon night when the Moon is not visible in the sky at all. Both occur periodically as part of the Moon's regular cycle of shape changes.
12What activities do birds, animals, and plants do at different times of day?
The chapter encourages students to observe and discuss how the behaviour of birds, animals, plants, and humans changes between morning, afternoon, and night, noting that their activities vary as the Sun moves across the sky throughout the day.
More chapters in Our Wondrous World
Read Chapter 10 of Our Wondrous World, the Class 4 The World Around Us NCERT textbook (2026-27 edition), online for free: the complete chapter as published by NCERT with every diagram, solved example and exercise, with step-by-step solutions, answers and revision notes. Open the NCERT PDF above, or browse all NCERT Class 4 textbooks.
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