sunsets and the sky

why the sky is blue and sunsets are red


  • transparent/clear container

  • water

  • milk or milk powder


  1. Fill the container will water

  2. Add a small amount of milk, about 1 teaspoon, to the water

  3. shine the flashlight through the container, the water should look blue, and the should be some orange directly from where the flashlight shines!

  4. Now, if you change the position of the flashlight, representing the different places we see the sun in the sky throughout the day, you should see more or less of an orange/red color just like the sunset!

Science behind the blue sky and the orange sunsets

The reason that our sky looks blue and the sunsets look orange and red is because when the sunlight passes through our atmosphere, blue light scatters the most. This is why our sky looks blue. But during sunsets the sunlight shines through our atmosphere at a different angle. From this angle we see orange and red. In the experiment if you place the flashlight at the bottom of the container and look at it from above, you should see mostly blue and a little bit of yellow. This is like when the sun is directly above us around noon and we see a blue sky. Now if you shine the flashlight from the sides of the container and look from the opposite side you should more orange and red. This is like when the sun looks like it is lower in the sky on the sides in the morning or night, and we see beautiful sunsets. The reason that we use milk is to represent the particles and clouds in our atmosphere.