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Assuming that the sky isn't that color because of excess pollution, would the makeup of the atmosphere need to change?
And if it were breathable, would the necessary position and color of the sun cause unliveable or drastic temperatures on the planet's surface?
In other words, assuming a world of humans with slightly advanced technology, is this aesthetic choice of sky color scientifically sound?
You would just need a little more atmosphere is all. The more dense the atmosphere, the less blue light that will be visible on the surface.
On Earth a sunset appears red because the light has to pass through more of the atmosphere before it reaches you. As a consequence more of the red light is scattered away, giving the sky a red appearance. This increased density could be caused by pollution, but it also could be caused by dust or water vapor or slightly increased gravity.
A good example is the planet Mars, where dust high in the atmosphere makes the sky appear red during the day and blue at sunset.
Most "Earth-like" planets may not have blue skies. Most stars are red dwarfs, which emit very little blue light, so even if there is scattering in the atmosphere of an Earth-like planet, there is simply very little blue light available. So, the sky would not be blue. But, of course, one would imagine that any creatures on such a planet would have eyes that were sensitive in the infrared instead of in the visible, since that is where most of the light would be.
More here: https://planetplanet.net/2015/09/16/the-colors-of-other-worlds/
