You can see my submission to the contest attached to this comment. Since dark matter is all about invisibility, I decided to modify the original picture mainly by using the delete tool.
I know I will be contesting against seasoned veterans like @agmoore, but something tells me I'm gonna leave her in the dust with this one. I mean, a picture is worth a thousand words, and just look at (or try to detect) the result of my artistic non-efforts below! Here it is:
Beautiful, isn't it?
(If you're having trouble seeing my submission, turn off the lights. If you're still having trouble, close your eyes. That oughta fix it.)