My frame of reference might be a bit skewed, but I spent most of my life in a city. The only time I saw nature or 'sky' was in the play room, but that was all fake. The sky outside was endless. You could see the stars forever, and the ships would come in and out all the time.

[ He was always working or training, so he wasn't aware of many other things besides what little he's seen and what was presented in books. ]

I had a friend who came from a deep sea planet. Her eyesight was bad due to it, but she really liked drawing jellyfish on everything and always had jellyfish gifts from home.