The photographs are exposed well and they work as photographic "sweets". They are fun to see for a few seconds but don't contain within a lot of reason to stay with them. This is typical of this kind of photography, whose aim is to capture a splash of color. In painting there used to be a county fair version of this called "spin painting."
The question is can you make these splashes more interesting, more powerful than they are now? In the case of the first, there is too much dead area. The sea of black isn't doing much work. Viewer understand what "night sky" is, so too much of it doesn't help. In the second, the colors aren't very punchy.
These are hard to do in a way that hold interest. The best ones I have seen have a visible b/g so that there is more content and more juxtaposition and more opportunity for interest.