# Why is the sky blue? [duplicate]

Possible Duplicate:
Why does the sky change color?

Basically what the title says. What mechanisms are significant and how do they contribute to make the sky blue. Also when the sky is not blue, like when the sun sets, how does it happen?

• Related to physics.stackexchange.com/q/17 Oct 15 '12 at 17:14
• Hello Andreas, Please have in mind, to refer to Wikipedia before asking such questions. It's also a duplicate... Be Careful while posting next questions.... Oct 15 '12 at 17:29

Because of scattering. Blue light scatters more then other colours, because of its high frequency.

• Even still, the lack of information might confuse some. The red light is seen because scattering is high and red light isn't as scattered because it has a high wavelength ($~700\text{ nm}$) and Rayleigh says that scattering is inversely proportional to the 4th power of the wavelength.