Why is the Sky Blue?

Have you ever looked up at the sky? Well most of us have at some time maybe at night or even in the day. I'm sure most of us would say that we have watched the sun rise or set at least once. Well have you ever wondered why it's the colour it is? Well maybe you have not, but some scientists did and they found out why! And now through the wonders of the British Education system I am now able to tell you why the sky is blue.......

Lets start at the basic level, the Earth is round and has a layer of gas around it called an atmosphere. The Earth orbits a star which we call the sun. It does not orbit it exactly dead on though, it orbits it at an angle. Right that should be everyone up to speed. Now to explain why the sky appears blue I must explain a little about the electromagnetic radiation (ER).

The sun gives off ER off many wavelengths or Energy levels. This energy travels in a straight line through space at the speed of light (c). Each energy level or wavelength has a different effect see diagram below:



So radiation from the sun hits our atmosphere mostly in the range of UV and X-ray. The earths atmosphere is a dense layer of gas and the photons (er) collide with the gas particles. When they collide they lose energy and so change their character. So:



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I hope this page has answered all your questions on this topic but please e-mail me if you need any more information.