May I offer you a warm welcome to the CameraLabs forum.
You specifically mention twilight photography. If you can accept long exposure times (no moving objects causing motion blur) then a compact camera may well do the job when mounted on a tripod. But there's no substitute for a bigger lens when it comes to capturing those photons and that usually implies buying into a camera system with a bigger sensor as well. Looking at your budget I'm wondering if the Sony NEX-3 might be an option? You can read Gordon's review here
to see how well the camera performs. If it is an option so far as both budget and size are concerned then you'd initially be throwing away the long telephoto capability of a superzoom but on the flip side you could start building a lens collection you wouldn't need to throw away every time you wanted to upgrade your camera.