How would a huge ball of air look in space from outside and from inside?

Question

If you replaced the Earth (except the atmosphere) with air and kept the pressure linear to the center (of the now non-existing Earth) while ignoring the effects this would have on gravity and leaving the solar system alone:

• How would it look from the outside (with and without the sun in view)?
• ...and from the inside (at multiple distances from the center)?

I'm guessing that based on Rayleigh scattering that it would look redder the more air is between you and the vaccum in the sun direction. No idea how it looks if the sun is perpendicular or at your back.

Answer 1

From the Outside

Your intuition is right. Rayleigh Scattering would come into effect, making the insides red and the outsides more blue.

If the sun is at your back, or if the angle of sun-air-you is a right angle, you will still see light coming off of the air. However, this reflected light may be faint enough in places that you get the color of the night sky/space.

There would also be rainbows/glories/halos, depending on the water content of the air you're looking at and the sun-air-you angle.

From the Inside

Rainbows and glories and halos would abound. Once again, it depends on where you are relative to the sun and the water within the air, but having a ball of only air makes the odds of seeing these much higher.

Rayleigh scattering would also be at work even without the help of massive amounts of water. Rayleigh scattering would give you a similar effect as looking from the outside into the middle.