You cannot see the wind, but you can see leaves shake.  You cannot see the Earth turn, but you see the sun move through the sky.  There are many things in our world that we cannot see, but we still know are there by how other things move.  Light is no different.  There are parts that you can see and parts that you can feel.  There are also parts that we only know about because of how other things move.  Just as you can feel the wind, you can feel heat from the sun.  Just as you can see the sun move, you can see plants grow when the sun shines.  There are more things happening than just what meets the eye.  Let's explore the dark side of light. 

Here comes light, shooting across space at 300,000,000 meters per second.  And then it hits Earth.  Splash!  You would think that would hurt us, but it does not.  It makes that car look pink when it bounces off it.  It makes that plant grow.  It gives that man a sunburn because he stays out in it for too long.  The electromagnetic spectrum is all of the energy that travels at the speed of light, or in other words all parts of light that we can see and the parts we cannot.  They all do different things, from helping life grow to helping us see.  Someone should give that man a hat.

Next time I think I'll wear sunscreen.

People lay out on beaches.  Dogs find triangles of sunlight to lay in.  Trees spread their leaves on sunny days.  The sun does not only give us light to see.  Most of the time, things have to be touching in order for heat to move from one thing to another.  But not all the time.  Heat can also move across space as light, without things having to bump into each other.  Radiation is another word for light that we feel as heat.  It is able to move from one place to another as a wave.  It moves off the sun, like ripples in water.  This kind of heat is different from all the others, since it does not have to move through stuff.  It can wiggle through empty space to reach us.  Everything gives off heat, even you.  But you do not give off as much heat as the sun.  We know this, because you don't have dogs lying around you all the time, or people laying out their beach towels at your feet for their vacation.

Now just where am I supposed to put MY towel?

You've probably heard people say "let's soak in some sun."  Almost everything on our planet soaks in the sun's energy: you, plants, elephants, rocks.  Even the air above your head soaks in some of the sun's energy.  To absorb means to take in.  Living and non-living things all take the radiation waves from the sunlight and store it as energy, use it for warmth, or turn it into into food.  It's like a thousand baseballs being thrown at you at the same time, and you try to catch as many as you can.  Instead of needing talent like you do to catch baseballs, you can just stand there and your skin will absorb it.  If only you could use that trick on the baseball field.

If absorbing light is like catching things with your skin, there are parts of the light that you hit right back into the air.  Sometimes light bounces in a line and other times it bounces off things as all the colors we see.  To scatter means to spread out in many directions.  Light bounces off some thing in a straight line and bounces off others in many different directions.  It depends what the things are made of.  A stop sign hits back red light while a yield sign hits back yellow.  When light hits the air above us, some of it is soaked up, but the rest of it scatters across the sky in every direction.  Can you guess what color scatters the most?  That's right: blue.

Never stop reading science.

There are many parts of light we cannot see.  It comes down from the sun and hits the Earth.  Some of it warms us.  Some of it we soak in.  Some of it we bounce back into the air.  There is more to light than meets the eye.  We just have to look to our other senses and how things move around us to know how it moves.



Kids Geo.  "Radiation"  Kids Geo, 2010.  <>

Optics 4 Kids "What is Optics?" The Optical Society, 2008.  <>