Luminous or not
Who makes light, and who only reflects it?
The Moon at night
Keshav looks at the moonlit hills from the bus. He remembers many songs about moonlight.
Does the Moon make its own light?
What this lesson covers
The idea
Objects that emit their own light, such as the Sun, stars and lightning, are luminous; objects that emit no light of their own are non-luminous, such as the Moon, which only reflects the Sun's light.
The Moon at night
Keshav looks at the moonlit hills from the bus. He remembers many songs about moonlight.
Does the Moon make its own light?
- Yes, it makes its own light
- No, it only reflects sunlight
- I am not sure
Sort the objects
Decide for each object: does it emit its own light?
Luminous and non-luminous
The Sun, stars, lightning and some animals, such as fireflies, give out their own light. The Moon only reflects the light of the Sun that falls on it.
Objects that emit their own light, such as the Sun, stars and lightning, are luminous; objects that emit no light of their own are non-luminous, such as the Moon, which only reflects the Sun’s light.
- Luminous | Non-luminous
- Sun, stars, lightning, a firefly, a lamp that is on | Moon, mirror, book
Notes
Objects that emit their own light, such as the Sun, stars and lightning, are luminous; objects that emit no light of their own are non-luminous, such as the Moon, which only reflects the Sun’s light.
Check yourself
Which of these is luminous?
Why can we see the Moon in the night sky?
An object that does not emit its own light is called …
Which of these emit their own light?
- A mirror. A mirror emits no light of its own. It changes the direction of light that falls on it.
- The Sun — correct. Yes! The Sun emits its own light.
- The Moon. The Moon is non-luminous. It only reflects the Sun’s light.
- It emits light like a star. Stars emit their own light. The Moon does not.
- It is a big lamp in the sky. The Moon does not emit its own light.
- It reflects the light of the Sun that falls on it — correct. Yes! Moonlight is reflected sunlight.
- non-luminous — correct. Yes! The Moon and a book are non-luminous.
- transparent. Transparent is about light passing through a material. It is a different idea.
- luminous. A luminous object emits its own light.
- A book and a mirror. Neither a book nor a mirror emits its own light.
- Stars and lightning — correct. Yes! Both emit their own light.
- The Moon and a book. Neither the Moon nor a book emits its own light.