The earth is very much visible to us, because we are on the inside of it with atmosphere.
If it were possible to dunk you in the vacuum outside of earth, you would not see earth, because there is nothing for your eyes to to receive light, because there is nothing for light to pass through "nothingness."
Obviously things can move through a vacuum. What do you think air molecules move through? Same with light, it doesn't need a medium because we know it's made of particles. These move through empty space, even when they are moving "through" air - they are moving through the spaces between air molecules. Of course they hit air molecules too, that's how light gets scattered. So your vacuum concept itself if incoherent.
Nothing moves in a vacuum .NOTHING.
No particles....NOTHING.
No light, which are just super agitated molecules/particles/matter, anyway...MOVES.
Come on Sceptimatic, think. Consider an individual air molecule, say an O
2 molecule. It's zipping around on its merry way, bouncing off of other air molecules and what not. There's no air surrounding it, because it
is the air, or part of the air. That molecule is surrounded by - empty space. And yet it moves, spins, etc. Whereas you are saying that
nothing can move in a vacuum.
A vacuum is zero pressure, so anything in it becomes zero pressure, which means the ice dome is at zero pressure.
Please note the part in bold, and stick to that. We can deal with ice dome pressure later. If nothing moves in a vacuum, how can air molecules move?