Hello and welcome back to Factually Deficient! I have such a wealth of lovely questions to answer that sometimes it’s difficult to choose, so this time I’m going to answer a question which I reason must be popular, because it was asked by not one but TWO discrete individuals (one known as Krika on twitter, and one known as Shari on the comments of this very blog):
Why is the sky blue?
This is a very interesting question, particularly as it presupposes the blueness of the sky. To the unwitting observer, the sky does frequently appear to be blue– but the truth of the matter is already hinted at in the facts that the sky doesn’t always appear blue (for example, at nighttime it seems black, while at sunset and sunrise it appears orangey or purple), and that rarely does the whole sky appear to be blue– generally, at least a few white clouds are visible.
In fact, the sky is (or at least, should be) a totally smooth shade of white. However, during its last cleaning cycle, the varnish on the sky got scratched. As a result, a blue stain has been spreading over it for the past few thousand years. You can still see the bits of the original white on what is known as a cloudy day– what is really happening is when the weather is rainy, the water washes the blue stain off, revealing the proper white, until the wash fades and the white shrivels into little spots against the blue, known as “clouds”.
The reason why the sky appears to be black at night is quite simple: The collective blackness from people closing their eyes and going to sleep (as everyone knows, when you close your eyes you see blackness) is in such large quantities at nighttime that it diffuses out from behind people’s eyelids and not only suffuses the air around you, but also tints the stain on the sky a very dark hue.
Similarly, during sunrise and sunset, the reddish orange light from the sun is particularly strong and particularly close to the stains on the sky, and so it colours the otherwise blue stain those lovely orange and pink shades.
And going back to the blue. If the sky at night is black because of people closing their eyes in such high numbers, and it is orangey purple at sunrise and sunset because of the sun’s rays, and it is white on cloudy days because that’s how it’s supposed to be, then why is it blue the rest of the time? Really, the answer should be obvious. In the absence of something else to influence the colour of the stain, all stains on anything naturally turn blue. That is the same reason why most bruises turn blue– because bruises are really just a temporary stain on the skin, and in the absence of something to influence their colour, they are simply blue.
Disclaimer: None of the assertions made in this blog should be taken as correct. The author does not recommend attempting to wash the sky, and does not actually approve of rainy and cloudy days.