I did the same thing last week. We used a rotating telescope with a dslr on the end. We also had a little gizmo that tracked arbitrary moving objects in the night sky and told the telescope which direction to move so as to keep the moving object in the same place.

Using 5-10 minute exposures, we were able to take the same kind of colorful astronomical pictures you would expect to see in NatGeo. It was truly amazing. You really don't pick up on the beautiful colours of the stars with the human eye.