Not Just for Kids
Why is the Sky Blue?
Story & Photo by Martha Blume
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| Alan and Phoebe Blume sail on blue water under a blue sky. |
Why, when you look up at a clear cloudless sky, is it blue? Why not peach or chartreuse or even purple?
Here’s an experiment to help explain why.
You’ll need:
- a tall, clear glass
- milk (low-fat works best)
- white paper
- a teaspoon
- a flashlight
- a dark room
Fill the glass with about eight ounces of water. Turn off the lights. Hold the paper behind the glass. Turn on the flashlight and shine it through the water so that the light shines onto the white paper. What color is the light?
Now put about one or two teaspoons of milk in the water. Shine the flashlight down into the glass. You will see a slight sky bluish color. Shine the light through the glass and onto the white paper. What color is the light now?
What happened?
Light is actually made of many colors — the spectrum — that you see when it shines through water droplets or through a prism and makes a rainbow. The colors are red, orange, yellow, green, blue, indigo and violet. You can remember this using the mnemonic ROY G BIV.
When you shine the light through the glass of water, the white light goes straight through and doesn’t separate into its component colors — unless you shine it at an angle at the surface of the water: then you’ll see the rainbow!
When you shine the light through the milky water, the milk looks blue and the light on the paper looks red. That’s because blue light is made up of very short wavelengths that are easily scattered when they hit the fatty milk molecules. Red light has the longest wavelengths and plows right through the milky mess. The same thing happens in the sky. The blue light bounces off dust, pollution and water droplets in the air and is scattered, just as it bounced off the fat molecules in the milk. So on a sunny day, the sky looks blue!
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What Am I?
by Jean Oaks
I scuttle sideways in the sand.
Folks must always understand
That, though my dance is fun to see,
They must take care when handling me.
I am measured by the inch.
I can really, really pinch!
My shell is blue when I’m caught,
But I turn red when steamed and hot.
Don’t you wonder, long ago,
However did somebody know
That underneath my shell was meat?
(Getting to it isn’t neat!)
But, oh, I’m really good to eat!
What am I?
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Word Attraction
Mnemonic
A mnemonic is a trick to help you remember. ROY G BIV sounds like a man’s name, but it’s a mnemonic to help us remember the order of the colors in a rainbow. The word mnemonic comes from a Greek word meaning to remember. A mnemonic for remembering the order of the planets in our solar system (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto) is My Very Energetic Mother Just Served Us Nine Pizzas.
Can you come up with some mnemonics of your own?
Kids Calendar
Thursday, May 13
Dinosaur Picnic
Kids 2-5 bring your favorite dinosaur and play games, make crafts and go on a dinosaur egg hunt. 11am-noon @ Mt. Hope Community Center, 100 Pushaw Station Rd., Sunderland. $2; rsvp: 410-257-6770.
Friday, May 14
My Friend Rabbit
Hear the story of the adventurous rabbit and all his friends; then make a take-home craft. 10am @ Barnes & Noble, Harbour Center, Solomon’s Island Rd., Annapolis. free: 410-573-1115.
Saturday, May 15
Buggy for Books
Kids 2-4 bring your parents for insect stories, activities and a buggy art project.
10-10:45am @ St. Paul’s Episcopal Church, 25 Church St., Prince Frederick. $5; rsvp: 301-367-3115.
