• Question: why is the sky blue?

    Asked by emdogpenghorton to Anil, Blanka, Cees, Emma, Mike on 26 Jun 2012. This question was also asked by issi2001.
    • Photo: Emma Trantham

      Emma Trantham answered on 26 Jun 2012:

      Hmmm really I think we need a physicist to answer this properly but I will give it my best shot…

      Visible light is made up of a spectrum of different colours (red, orange, yellow, green, blue, indigo, violet). Each of these colours is caused by the light wave having a different wavelength. Red has a long wavelength whereas violet has a short one.

      When white light from our sun passes into our atmosphere the long wavelength light waves (red, orange, yellow) pass straight through the atmospher. The shorter waves (like the blues) get absorbed by the gas molecules in the atmosphere. This absorbed light is then scattered in different directions and it is this scattered blue light that we see in the rest of the sky.

      (If we were silly enough to look directly at the sun – DONT DO THIS- then we would see all the colours of light which is why the parts of the sky nearer the sun look whiter than the parts further away.)

    • Photo: Blanka Sengerova

      Blanka Sengerova answered on 26 Jun 2012:

      Ahh, the typical question. But Emma has got it pretty much covered – doing a bit of a google, I’ve found this nice explanation which goes into more detail into essentially what he has just told you: http://www.sciencemadesimple.com/sky_blue.html