Why is the sky blue?
Sky is blue because of the presence of atmosphere.
The particles in the atmosphere scatter the incident sunlight, giving the blue colour to the sky.
Had there been no atmosphere, sky would look black, like at night .
EDIT: As to why the sky is bluish, and not any other colour, has to do with the wavelength of the different components of White light.
White light , or VIBGYOR (acronym for Violet, Indigo Blue Green Yellow Orange Red) , in terms of wavelength, looks something like this.
As you can see, the blue light has the shortest wavelength, which means that it is scattered the most.
As you can see, red is scattered the least. That is the reason it is used in danger signals.
Like NASA says :
- Blue light is scattered in all directions by the tiny molecules of air in Earth’s atmosphere. Blue is scattered more than other colors because it travels as shorter, smaller waves. This is why we see a blue sky most of the time.
