So the atmosphere interacts with light because it’s there, not because it interacts with light??
I’m saying if the atmosphere was smaller, scattering would be less and blue colour may not appear. So the blue colour is not because the atmosphere is “not entirely transparent” like the commenter said, but because there is enough of the atmosphere that the scattering effect is prominent.
And yet, if the atmosphere was fully transparent, there would be no scattering of light. The blue colour is an effect of the amount of air, but there would be no colour at all if air was fully transparent.
That is funny. According to you, for a medium to be called “fully transparent” there has to be no scattering of light. By that definition, water and air are not “fully transparent”. I’m not sure if such a material exists that doesn’t scatter any amount of light.