Sunset in a Box

What makes a sunset red and orange? Kai shows us how to make a mini sunset to investigate this beautiful phenomenon of light.

Kai: I like to make things and learn about things in my own way. I’m Kai and I’m a hacker.

Kai: Light is energy. We can learn about energy by looking at light close up, like the beautiful colors of a sunset. How does that happen? Light has different wavelengths like blue and yellow and red light. At sunset, when the sun is low on the horizon, the rays of light have to travel through a lot more atmosphere to reach us.

Kai: Blue light scatters more than the other colors, leaving a yellow orange hue to the transmitted light. Today I’m going to show you how you can make your own mini sunset in a container! You’ll need some whole milk or milk powder, a flashlight, and something to stir with, and a rectangular clear plastic container with water. So, let’s see what happens when I shine my flashlight through it. Nothing much. You can see the light shining straight through the water. Now let’s add some milk and give it a stir.

Kai: Lights out! Now I shine my flashlight through it and look! It’s like a sunset! See the yellow and orange glow? The milk acts like the dust particles that are in our atmosphere, scattering the light. The milk particles scatter blue light leaving the orange and yellow light, which are longer waves. They can go through the particles more easily. So there you go! Your very own mini-sunset!