Is the Sky really blue

[cris r]

I have just been having an argument with my son I say the sky is not really blue we just perceive it like that (not that i know what colour it really is)

[wildwood]

But isn't that true of everything we can see? If it looks blue to you, it is blue. When it looks gray, it is gray. What you really see is the reflection of the sun in the air. When you look at the same piece of sky at night it is not blue anymore but its colour hasn't changed, just the light reflection properties.

AFAIK Colour is how we perceive the light reflected from an object due to its molecular structure, it does not emit that colour. If an object absorbs all the colour frequencies except the green spectre, it will look green to us. A very good example is a fluorescent colour which changes due to which angle it is viewed. We know for sure that some insects can see a whole range of colours which we can not see, due to the different cone cells in their eyes.

[Ice.Maiden]

Yes, without getting all technical, the sky we see on a clear day IS blue, because molecules in the air scatter blue light from the sun more than red light (from the sun itself). The while light from the sun is like a prism and contains all the colours of the rainbow, but what you're seeing is the mass of blue. Oh dear - i THINK this's right. School was a few year's ago now!! x