This was going to be a totally different astronomy painting. Whenever I do one, I actually do bother to manually paint the background black, instead of just setting it that way. Partly, I just find it satisfying- but partly, sometimes things like this occur. I was halfway through turning the canvas black when I noticed that the brushstroke's texture and curve against the white made it look a hell of a lot like the boundary between a black hole's accretion disk and its event horizon, viewed from a disquietingly close angle. A few streaks of paint later to add some texture to the white hot accretion disk, and I had one cool and easy painting on my hands. Given the low amount of effort and the simplicity, this is firmly a sketch to me- but still, isn't it cool?
Here's the black hole from the movie "Interstellar" for comparison.