Okay, so I was messing around and I created an extremely massive black hole.
Then, I put the Sun into orbit around it. I had to put it far away so that the orbital speed was below the speed of light, just so that I wasn't breaking the laws of physics or anything.
(it was really far away)
But I wasn't satisfied yet. I wanted to go further. So, I decided to put some planets in orbit around the Sun. And then... this happened?
I guess the game isn't really equipped to handle these kinds of distances/speeds/whatever is causing this to happen...
Here's the simulation if you want to check it out for yourself.