Alley's got the brands right I think, and for my money Nikon is the best bet, though it depends what you're comfortable with. I bought a Nikon after handling several Nikon and Canon models, and the Nikon just felt better in my hands and the controls--at least the ones I'd use the most--seemed more conveniently placed to me. Night sky photography is pretty tricky though, regardless of your equipment. You'll certainly need a good tripod, and a remote cable or electronic shutter release will prevent camera shake when you press the shutter button. You'll need long exposures to photograph constellations, the camera doesn't respond in anything like the way your eye does, and I really doubt you'll get good images from ordinary camera lenses. I think you need a small telescope if you want to get serious about this. For starters I suggest you drop in to your favourite book shop and pick up Terence Dickinson's book NightWatch, it's a practical and very useful guide. Be sure to get the 4th edition, the 3rd is out of date in terms of celestial events worth watching. #juan is the local expert here, drop him a PM, I'm sure he'd be happy to advise you.