Hollowing out a planet to build a massive gun in it would be really silly.
Our planet consists mostly of molten metal. Molten! Hot and liquid. If you would liken our planet to an apple, the Earth's crust would be as thin as the apple's skin.
And even if that hollowed out planet would be a tenth the size of Earth and in a completely solid state then you would still need to expend massively incredible amounts of energy just to keep the top and bottom halves of the planet from collapsing on themselves from their own gravity.
Therefore, I really hope that was we are seeing is like a death star and not a hollowed out planet.
Still. I really hate that it could be either.
I had planned on taking the opening day off so that I could see the movie as early as possible. Now, I'm not so sure that I am going to do that.
That's a story arc from Battlestar Galactica, right?