If you give a concise definition of the radiation, we can say that this stream waves, carrying energy. If we make a hand around a burning candle, we feel as heat. If we look at the sun, we see the light, which is also is the wave only visible to our eyes. You can give many examples of this phenomenon, so let's start from the beginning. What is an electromagnetic wave and how it occurs, we will not talk. Let's just imagine looks like the wave in the figure (). The distance between two nearest ridges called wavelength.

It is important to understand because This indicator is the determining factor for the grouping of the waves on their properties and manifestations. Thus, waves with the shortest length is called the X-rays. They opened a physicist: Wilhelm Conrad Roentgen (during which he received the Nobel Prize). This type of radiation has good penetrating ability, so prevalent in medicine. As you've probably heard: X-rays harmful to humans and living organisms.

And if from outer space enters this type of radiation, but because of their aforementioned ability of his little What can stop them. But the layer around the earth under the name "magnetosphere" retains many of the radiation from space. The next type of radiation in terms of wavelength is "ultraviolet radiation". This radiation is also harmful to living organisms, but most of the ultraviolet light does not pass through the Earth's ozone layer. But some of the ultraviolet light is adjacent to the light rays, and this becomes the cause of our sun.