What Colour Is The Sky?

What colour is the sky?

Seems like utter child’s play, right? Right?

The sky’ s blue, of course! You can certainly go out in broad daylight and confirm that, yes, the sky is, indeed, blue.
But, what colour is it at nighttime? What about at dawn or dusk? What colour is it on a cloudy day? What about those who look up in a big city on a smoggy day?

What about those who were born blind, or those born colour-blind? At night, there seems to be no “sky” at all.
At dawn and dusk, nearly every colour but blue is visible and in a gradient from dark to yellow as it progresses towards the Sun.
On cloudy days, the clouds prevent the sky from being directly observed; so, does the sky still behave on cloudy days like it does on sunny ones?
One would need to go above those clouds in order to find out. Frequent fliers should be able to answer this question.
Similarly, those in smoggy cities will need to be able to view their sky from above the layer of smog itself. Inability to see anything prevents blind people from answering this query via direct observation, so they must rely on intuition and logic. They may accept the sky’s colour as blue because that is what everyone around them says it is; but, it is more likely that the multitude are wrong than right – particularly when it comes to things that cannot so easily be directly observed.
Relying on consensus of the majority is illogical. Colour-blind people have a problem of their own; they can see the sky, but it may not appear blue to them. Again, relying on majority consensus here is illogical; how can we confirm if the daytime sky is truly blue?
How do we know that colour-blind people are not seeing things truer than we “normal” people are?
The multitude are often wrong, so what if the sky is not blue after all?
What even is the colour “blue,” anyway?

Incredibly, something as outwardly straight-forward as “what colour is the sky?” has quickly become a very complex query simply by asking questions no one else feels the need to ask anymore.