• Question: Why is the sky blue

    Asked by Jayaarrrr to Daniel, Freya, James, Miranda, Usman on 17 Jun 2015.
    • Photo: Miranda Jackson

      Miranda Jackson answered on 17 Jun 2015:

      The atmosphere refracts (bends) sunlight as it approaches the Earth. The red portion of the spectrum is affected most by this. That is why the sky turns red at sunset, because we are seeing the light that is bent the most from where it first encounters the atmosphere. The light that is left over after the red light is redirected is blue, and that is why the sky appears blue during the day, when the sun is directly overhead.

    • Photo: James Gilbert

      James Gilbert answered on 18 Jun 2015:

      The molecules in our atmosphere ‘scatter’ blue light more than the other colours. Scattering is the process of bouncing light off in lots of directions rather than letting it ‘straight through’. So when you look at the sky, you’re seeing blue light that’s being bounced in your direction even though it arrived on Earth from a different direction.

    • Photo: Freya Wilson

      Freya Wilson answered on 18 Jun 2015:

      The particles in our atmosphere cause the mix of colours of light from our sun to scatter. It’s something called Rayleigh scattering. It does affect blue light more, so that is the bit which scatters such that it can come down towards us, to enter your eyes and show you the blue colour. If the angle is more direct- so light that comes directly from the sun in a straight line without hitting much then something happens called Mie scattering which doesn’t depend on colour. So if you look at the patch of sky nearer to the sun it looks a much lighter almost white colour than the deeper blue of the sky away from the sun.

    • Photo: Daniel Hewson

      Daniel Hewson answered on 18 Jun 2015:

      The sky is a Tyndall blue, named after the scientist who first explained the phenomena. It is all a matter of size and length. The size of the liquid and solid particles in the sky are smaller than o.0007 mm which the shorter blue wavelengths of light hit as they pass. Blue light is then scattered all over and eventually to earth. The longer wavelengths of light (green-red) pass straight through and carry on unaffected.

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