Why Is the Sky Blue?

September 29, 2009

by Eliza Clark

Do you have a curious preschooler on your hands?  Have you dodged or fudged this very question more than once?  Dodge no more, for Savvy has a (kind of) simple answer.  Talking points, if you will, for any atmospheric questions that may arise during your daily walk to the park.

Before we get into the (ahem) hard science, a few notes about taking on these kinds of kid questions in the first place.

Much as we enjoy being idolized of as all-knowing deities, it’s not strictly necessary nor particularly educational for parents to pretend to understand everything about everything.  The point of encouraging curiosity, we must remember, is to give kids an idea of how to go about learning the things they want to know.  

You can start by asking your inquisitive sky-gazer what else he already knows about the color of the sky.  Is it always blue?  Every kid knows about rainbows and gray days, and from there he’s already partway to the answer he seeks.  

The next step would be to speculate about possible explanations together.  What’s the difference between blue skies and grayer days?  When do rainbows appear?  Where does light come from?  What is the sky made of?  Write down all of his ideas – who knows, they may not be too far off.

Finally, you can investigate together.  Look it up.  That’s what we did, and here’s what we learned.  “There is a physical phenomenon called Rayleigh scattering that causes light to scatter when it passes through particles that have a diameter one-tenth that of the wavelength (color) of the light.  Sunlight is made up of all different colors of light, but because of the elements in the atmosphere the color blue is scattered much more efficiently than the other colors.”  For more details, see here.

So there you have it.  The answer is interesting, but we bet that the discussion leading there was even more so.  Here’s to blue skies!

Comment(0)

Share From Send A Link To Your Comments:

Bookmark

RSS