• Question: why is the sky blue and not purple or red or any other colours?

    Asked by han22511 to Antoine, Daniel, James, Julie, Saima on 9 Nov 2013. This question was also asked by anon-39618.
    • Photo: Antoine Buchard

      Antoine Buchard answered on 9 Nov 2013:

      Hello han
      Thanks for your question!
      The light coming from the sky is white but in reality it is made of all colours of the rainbow.
      Our eyes can receive receive direct light from the sun, hence white, but there is also a lot of light that we receive indirectly, and which is coming from everywhere in the sky. The molecules in the sky tend to scatter the blue component of the white light more, which is why the sky is blue. At dawn and dusk the sky appears red as direct light from the sun is now passing through more of the atmosphere to reach us. All of its blue light is scattered, so only the reds are passing straight through to your eyes.

    • Photo: Julie Speakman

      Julie Speakman answered on 10 Nov 2013:

      And don’t forget you DO see lots of different colours in the sky, depending on weather conditions, where you are, how much pollution there is…..

    • Photo: Saima Rehman

      Saima Rehman answered on 11 Nov 2013:

      Yes, it would look wonderful if it was purple..as its my favorite color. Anyway, the sky is blue because this color is strongly reflected back to our eyes through the small particles and dust in sky. You can do a small experiment, if you shine a white light (which is a mixture of 7 colors, as in rainbow, imagine this is your sun) on a bowl filled with soapy water (imagine the top layer on water makes your sky). You will see blue color and not any other color.
      Does it make any sense, han22511?

    • Photo: James Hickey

      James Hickey answered on 11 Nov 2013:

      Hi han22511! You have probably got the answer you wanted now, but in summary:

      • Light from the sun is made of 7 colours (red, orange, yellow, green, blue, indigo, violet) but we see the mixture of this as white.
      • Sunlight travels through the sky above us.
      • It is interrupted and scattered by really small particles.
      • Blue light is scattered the most.
      • Our eyes receive the blue light and we therefore see the sky as blue.

      Hope this helps 🙂

    • Photo: Daniel Patten

      Daniel Patten answered on 12 Nov 2013:

      Hi @han22511,

      I think your question has been more than answered above, but here’s a link to images of lots of different colours in the sky https://www.google.co.uk/search?q=northern+lights&tbm=isch&tbo=u&source=univ&sa=X&ei=vO2BUvayGvHB7AautIC4BQ&sqi=2&ved=0CFoQsAQ&biw=1366&bih=641

      The ‘Northern Lights’ (posh name Aurora Borealis) are causes by clouds of charged particles (ions) in the atmosphere.

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