Sky is made of air. Air is colourless, and space is black. So it has to be the sunlight hitting the air to cause the colour. During most of the day, the sun hitting the air makes it look blue. When the sun is at a different angle, such as dawn and dusk, it looks red/orange. The chemical composition of the air doesn't change, nor does the colour of space. The only thing that's changed is the angle/amount of sunlight. Thus, we can infer that while the sky appears blue, it's not due to it being inherently blue, but rather it's blue due to sunlight hitting it at specific angles.
If you were observing the same orange sunset a couple time zones away, under the same sky, made of the same oxygen, nitrogen and carbon dioxide, at the same moment in time, it could be mid afternoon and the sky is perfectly blue.
This may be slightly simplistic
Sky is made of air. Air is colourless, and space is black. So it has to be the sunlight hitting the air to cause the colour. During most of the day, the sun hitting the air makes it look blue. When the sun is at a different angle, such as dawn and dusk, it looks red/orange. The chemical composition of the air doesn't change, nor does the colour of space. The only thing that's changed is the angle/amount of sunlight. Thus, we can infer that while the sky appears blue, it's not due to it being inherently blue, but rather it's blue due to sunlight hitting it at specific angles.
If you were observing the same orange sunset a couple time zones away, under the same sky, made of the same oxygen, nitrogen and carbon dioxide, at the same moment in time, it could be mid afternoon and the sky is perfectly blue.