Lightning in space?
Well, I'm guessing the high saturation and brightness is due to the GBA's reduced saturation screen. Keeping that in mind, the moon is nice. the stars can use some variation in brightness, as well as maybe cross AA. The "rip in space time", well, looks too rigid. Think of a rip in fabric, and you should accomplish the right effect. "Rips" are not "cracks". Besides that, the stars moving towards the "rip" is a nice effect, though I think you should try to have them moving at an angle perpendicular to the closest, err, segment in the "rip".
Hope that made sense. And I'm not sure about your color restrictions, so some of my critique may be inapplicable in this case.