• Question: Why does the shy turn pink at dusk sometimes?

    Asked by Gabriel_tekkers to Chris, Josh, Rebecca, Rob, Susan on 17 Jun 2015.
    • Photo: Susan Cartwright

      Susan Cartwright answered on 17 Jun 2015:

      The atmosphere scatters light. It preferentially scatters short wavelengths, which is why during the day the sky is blue. But at dusk (or dawn) the sunlight has to travel through a lot more atmosphere, so more scattering takes place and the sky becomes greenish or, if there is high cloud to enhance the scattering, pink.

      In the years after powerful volcanic eruptions, which blow fine dust high into the atmosphere, you get extremely spectacular red sunsets and sunrises, because of the extra scattering. This may explain the vibrant sunsets painted by the 19th century painter JMW Turner, following the 1815 eruption of Mt Tambora.

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