Hi Allison,

That is a very good question!
The answer is pretty complicated: UV rays are just one form of light that you can't see.
All light consists of rays, but they can have all kind of "colors", or wavelengths, as scientists say.
There is light with really long wavelengths that people can't see, such as radiowaves, and infrared.
If the wavelength gets a bit shorter our eyes can see it: from red to orange and blue, like a rainbow.
If the wavelength gets even shorter, we can't see it anymore, and that would be UV, and the X-rays your dentist makes.
The sun radiates all of those colors, in different amounts. Our atmosphere, with the famous ozone layer, protects us from radiation that can harm us: if you stay in the Sun too long you can get sunburnt, and it can damage your eyes!
However, it also has good effects: you get a beautiful suntan, and your skin makes vitamin D.
Just be smart, use protection and don't go sunbathing all day!

A webpage is http://hyperphysics.phy-a....edu/hbase/ems3.html

Mandy

Hi.
As you know, light comes in many different colors. Light can be thought of as being a wave, and colors are how our eyes interpret different wavelengths of light. Our eyes can only see light in a certain range of wavelengths (which we call 'visible' light). Light with wavelengths a bit longer than what we can see we call "infra-red' light (below red). Light with wavelengths shorter than what we can see we call 'ultra-violet light', or 'UV' light (beyond blue).

Most UV light is blocked by the Earths atmosphere (specifically the ozone layer, which you may have heard of), but the UV light that does get to the surface can burn you skin and can cause skin cancer.