• Question: WHY IS THE SKY BLUE

    Asked by ALICE to Koi on 23 Jun 2016.
    • Photo: Arporn Wangwiwatsin

      Arporn Wangwiwatsin answered on 23 Jun 2016:

      Hi ALICE,

      It’s to do with the how objects absorb and reflect light. Light actually composes of many colours (scientifically referred to as “spectrum”). When it hit an object, some of these colours are absorbed, while some are reflected. An object like, let’s say, a green t-shirt, when it is hit by light, it absorbs other colours and reflect the green colour, hence we see the t-shirt being green.

      Now, in the sky, there are actually lots of tiny little objects like molecules of gas and other particles. These tiny objects happen to absorb other colour of light and reflect blue, hence we see the sky being blue.

      This website has a nice diagram to explain this, and it even go further and explain why the sky look red instead of blue at sunset. http://spaceplace.nasa.gov/blue-sky/en/

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