As you mentioned, you are not a professional photographer or not even a beginner. And i assume you wouldn't want to carry a bulky camera with you around when you're travelling. I would suggest you something that is capable to capture milkyway and northern lights.

So here is my suggestion, Sony NEX-5 with 16mm f2.8 pancake lense and optional VCL-ECU1 wide-angle converter (this allow you to capture wider scene). And get a sturdy tripod for NEX, 1 option is fotopro c4i which is perfect in weight and size for travel.

I hope you also have the knolwedge on how to capture them, because they're not easy to capture, you need to do a lot of planning such as the location the you're going (must avoid light pollution area), time (when milkyway start raising up above horizon), and weather (if it is too cloudy/raining). From my milkyway shooting experience, the planning and luck is far more important than your equipment.

On the other hand, if you're more serious about photograpy, you can look into getting a DSLR with a wide angle lense. And i personally using Canon 60D with 10-22mm, this combo is quite cheap in the 2nd hand market.

Hope it helps.