It’s an age-old question: Why is the sky blue?
With this week’s Saturday Science experiment, from Sciences 360, you can do more than answer this question when your kiddos ask; you can show them, too!
- Clear glass cup
- Pour some water into the glass cup.
- Shine the flashlight through the sides of the glass. The water should be clear.
- Keep the flashlight light shining through the glass and add drops of milk to the water one at a time.
- Keep adding drops of milk until your mixture becomes blue.
Why did the milk turn your water blue? For the same reason the sky is blue!
Milk contains tiny molecules of protein and fat which are nearly the same size as atmospheric dust. As you added drops of milk to the water, the beam of light emitted by your flashlight hit these tiny molecules, absorbed the energy, and then re-emitted it in different directions.
The same thing happens in our atmosphere when sunlight encounters tiny bits of dust. According to Sciences 360, “These particles absorb energy from the incident light, vibrate, and then re-emit the light, scattering it in all directions.” While all colors are scattered, blue and violet are scattered the most. This phenomenon is known as Rayleigh scattering.
Rayleigh scattering makes our milk mixture and our skies blue because it is the blue light that reaches our eyes, which are more sensitive to blue than violet.