Blue sky red sunset colours

Use a glue stick and flashlight to model why the sky is blue and sunsets are red.
Science content
Physics: Light and Sound (1)
Earth/Space: Weather, Seasons, Climate Change (K, 1, 4, 7)
Lessons activity is in
  • glue stick
  • flashlight

Knowing sunlight is a mixture of colours, we can figure out why the sky is blue, and sunsets are red.
Distribute glue sticks and flashlights.
Tell students the glue stick models our atmosphere. and the flashlight is the sun.
Challenge them to shine the "sun" through the "atmosphere" and look for a blueish sky colour, and a red-orange sunset colour.

Blue: Sunlight hits the atmosphere and is scattered in all directions (O2 and N2). Blue light is scattered more than other colours, so more blue reaches our eyes from all parts of the sky.
Red: As the sun gets low in the sky, its light passes through more atmosphere to reach you. Most of the blue light is scattered, so only reds/yellows reach your eyes.


Or add a little milk to water, and shine a flashlight through it to see the blue colour. Add more milk to see the red/orange colour. (Weather Watcher p.60. DK)

Grades taught
Gr 1
Gr 2
Gr 3
Gr 4
Gr 5
Gr 6
Gr 7