Does that mean, in theory, that one could make a planet with a massive chunk ripped out of it if they wanted? Or even a planet with a chunk ripped out and awesome constructionish stuff spanning said ripped-out-ness?
Yes and no. Yes you can do it but unless you are really, really good with mind tricks it will not going to look good.
If you look closely you can see that the 'other side' is not showing, you basically don't see the inside of a planet. Which means that the backside of the picture used is not shown.
I'm not sure how to explain it...
Perhaps like this, take a planet's picture, erase a left or right half of it completely. Look at it in the game as it spins, if the side facing you is not transparent then you see it as normal, but when the side that is transparent faces you, you see nothing at all, not even the other side which is not transparent that is now on the backside of the planet not facing you that you should be able to see because the side facing you is transparent. It's like that. Basically.