Everything about life has to do with science, even the beautiful colors of the sky and the Sun at sunsets and sunrises. Actually the Sun is white. This is because the hot Sun emits all the visible colors of light and when blended together they form white light. Maybe a better way of saying this is that when the light sensitive cells in our eyes receive all the visible colors of light at once, the coded message they send to our brains is decoded as white.
The Sun appears to be different colors because as its light passes through Earth’s atmosphere some of the visible light colors are scattered. You see a bright yellow sun and a red sky, which indicates that red light from the Sun was scattered by gases in the atmosphere Blue light is often scattered and that is why the sky looks blue. The remaining colors coming from the Sun generally makes it appear yellow–sometimes orange.
Try This!
You can use a flashlight to demonstrate the scattering of light by Earth’s atmosphere. Instead of using gases, water with a few drops of milk works well.
1. Fill a transparent glass with water.
2. Set the glass of water on a flat surface near a wall. You want to secure a white sheet of paper to the wall to act as a screen. (You can use anything white, even the wall or poster board.)
3. Darken the room, and hold the flashlight so that its light shines through the water. You will see a pale yellow spot on the paper and the water looks clear.
4. Add a drop of milk to the water and stir.
5. Again shine the light through the water and note the color of the water as well as the spot on the screen.
6. Repeat steps 4 and 5 until there is no further changes observed. Note that the more milk in the water the more redish is the spot and the cloudier (bluish) is the water.
What’s Happening!
Like particles in Earth’s atmosphere cause different colors of visible light to be scattered, the fat globules in milk cause colors of visible light from the flashlight to be scattered. The color of the circle on the screen reveals the colors of light that pass through. Just like the glass of milky water, sometimes particles in the atmosphere scatter different light colors causing the sky to be colored. The light that passes through the atmosphere gives Sun its color.
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