Sky in a Jar

What you will need:

• a clear, straight-sided drinking glass, or clear plastic or glass jar
• water
• milk
• measuring spoons
• flashlight
• a darkened room

Instructions:

1. Fill the glass or jar about 2/3 full of water (about 8 - 12 oz.)
2. Add 1/2 to 1 teaspoon milk and stir.
3. Take the glass and flashlight into a darkened room.
4. Hold the flashlight above the surface of the water and observe the water in the glass from the side. It should have a slight bluish tint. Now, hold the flashlight to the side of the glass and look through the water directly at the light. The water should have a slightly reddish tint. Put the flashlight under the glass and look down into the water from the top. It should have a deeper reddish tint.

What's happening:

The small particles of milk suspended in the water scattered the light from the flashlight, like the dust particles and molecules in the air scatter sunlight. When the light shines in the top of the glass, the water looks blue because you see blue light scattered to the side. When you look through the water directly at the light, it appears red because some of the blue was removed by scattering.