Why is the Sky not Violet?

thinkdive.com (28)

“Have you asked a beautiful question today?”

Many of us ask our children , “What have you learnt in preschool or school today?” but maybe we should ask then if they had asked a beautiful question instead. Question asking is necessary part of the learning process and it is a great way to spark curiosity and interest. This approach was use by the Isidor Isaac Rabi’ mum (he grow up to become a great scientist). and she always asked if he had asked a good question. You can read more about question asking in the book A More Beautiful Question: The Power of Inquiry to Spark Breakthrough Ideas by Warren Berger

“Why is the sky blue?” is one of the most common child’s question. This question has been explored by scientists such as Aristotle, Leonardo da Vinci, Issac Newton, Johannes Kepler, and Albert Einstein. It is a deceptive easy question and it has taken many years to answers it. And many different branches of science has been involved in the search for a solution.

Yet it took years before the blue sky was a problem. We often take things for granted when we see it every day. It is believed that Aristotle was the first person to ask why the sky is blue. He suggested that the air close to you is clear and the deep air of the sky is blue, for the same reason that water is clear but it look black if you look into a deep well.

An explanation such as the air looks clear when it is thin because the tint is so faint does not really explain the blueness of the sky. For a long time it was suggested that something in the air modified the light and made it look blue, eventually scientists realised that the air itself make it appear blue. Air consists of gaseous molecules that make it look blue. The gas molecules in the air makes the light in the blue spectrum scatter more.

But violet light has a shorter wavelength than blue light, so why is the sky not violet? Part of the explanation is that our Sun produces more blue light than violet (you can read more about that here). But this puzzle also has a  biological part – our eyes are more sensitive to blue than violet light.

  • We simply do not see violet light as well as blue light so that is why the sky does not look violet to us!
  • But to some birds the sky may look violet!

Now let us have some fun with this information. Let’s think dive into what might be if we saw a violet sky.

  • Would violet and purple be the most popular colour instead of blue?
  • Would we have purple jeans instead of blue jeans?
  • Would there be violet flags instead of lots of flags with blue in them?
  • Would we have purpleberries instead of blueberries?
  • Would we build  orange houses since orange looks great against purple?
  • More yellow cars since yellow looks nice against a violet sky? Or maybe more violet cars?
  • Violet tits instead of blue tits, purplebells instead of bluebells?
  • Violet eyes instead of blue eyes?

Thinking about the consequences of something is a great way to give the thinking muscles a real work out. What does your world with a violet sky look like?

I am making a mind map where we are exploring consequences so look out for that blog post.

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