Why?

Oxygen has a lot to do with it.

There are some good explanations of this to be found on the interweb, but my first thought is that it depends upon which planet you are viewing it from.

I have rose tinted spectacles and , well, you can imagine the confusion.

If we get to vote, I'd like green. This may ruin landscape photography but it's my favourite colour. Ordinarily I'd run with Brit Racing Green, but the sky needs to be a milder shade of green. So called 'hospital green' would be horrible. It has to be, if gtreen is acceptable, a sot of grass coloured green.

Do you seek explanation, or is this a 'let's take a vote on it' thing ?

Light is diffused/filtered by our atmosphere and blue light is mostly what reaches us.

I hate to say it, but that's not a clear explanation. We need something here about refraction, 'what happens when light hits a prism', and that sort of stuff. You know, all that tech stuff.

Far be it from me to egg anybody on. Please add explanation of nice orange sunrise and sunsets for me .

OOPS! redfred already posted this at #9.

Go to this site, it says it all much better than I can:

Why is the sky blue? :: NASA's The Space Place

A prism is a specially shaped crystal. When white light shines through a prism, the light is separated into all its colors.

Sometimes the whole western sky seems to glow. The sky appears red because larger particles of dust, pollution, and water vapor in the atmosphere reflect and scatter more of the reds and yellows.

The pretty pictures and graphs do not copy well.

That's fine. I'll bide my time then give a digest of all the posts in about a week. All those GA's will be MINE !

If it was green when would you know when to stop mowing the lawn?

Because of all the oxygen. A bit more sulphur dioxide and it will be white instead.

....aggggghhh....rene us on zee way !

It may be more about diffraction than refraction. As light strikes atoms in the atmosphere, it is scattered. The redder frequencies pass along relatively straight (less scatter), while the bluer frequencies scatter more to the side.

Observing sunrise and sunset, you are looking mostly at the near straight-on light, hence reddish. The light from the overhead sky is more of the sideways light, hence bluish.

NASA has a nice page on this. The basics are that the shorter wavelength of blue light is easier for our atmosphere to scatter than the longer wavelengths.

shorter takes the scatter prize

What bothered me when I was very young was; "How do they know that that colour is named blue"

Blue is actually the perceived color that is bounced back to us.

Without humans, color doesn't exist...nor does time.

It almost leads one to wonder, that if without human observation, anything exists at all.

Whoever voted me OT, needs to read up on color.

The colors that we perceive and assign names to, are the color frequencies that are reflected back to us, and not absorbed.

I'll be happy to accept any challengers...but I guess that wasn't the point.

You managed to piss me off with your lack of understanding and an OT vote, so I suppose it's a win for you. Nice job!

mot me

They do it to get under my skin, and I play along by feigning anger. It's a CR4 thing.

As long as everyone's having fun.

Doh!!!

I have friends whose dog knows when it's 7:00 PM. He gets a pig ear at that time every night.

He starts looking at them about 5 minutes before, to be sure they don't forget.

Didn't you read Kramarat's word? Without people there would be no time and no color and possibly no existence all together. Surely it must be so. Anyone who doubts is instructed in his follow up response (to himself), to do penance by looking up the 'color' article in Wikipedia.

I'm guessing probably no anthropomorphic conceit would exist either....

Sometimes I like to try to expand my knowledge.

http://www.askamathematician.com/2012/06/q-do-colors-exist/

http://www.bbc.co.uk/news/science-environment-14421303

Yes Tinac...even time can be problematic.

http://discovermagazine.com/2007/jun/in-no-time/#.UxxF64WdMsA

who is going to win the Freski's prize???? Come on, come on, more participation guys,,,

Depends on what time of day you're looking doesn't it?

And how polluted your air is.

And what kind of weather you're having.

The sky over MY house is blue right now - due to Rayleigh scattering from O₂ molecules, the lack of air pollution or clouds, and the fact that the Sun hasn't set yet.

By the way - this scattering phenomenon is why green lasers make better laser pointers at night than red ones. The green wavelength is shorter than the red wavelength, so it is scattered more by fine water molecules and dust particles in the air than red laser light is. And it's also why green lasers work better as nighttime laser pointers in the Summer than the Winter - there is more humidity and dust in the air in the summertime than in the wintertime to scatter the light.