Alright, so on the subject of life on other planets...
Let's say, just as a hypothesis, that we discovered a whole planet very much like ours, but some millions of years before the evolution of ours. Basically, stuff like dinosaurs, and all that. What would be the reaction of the scientific community? Would we play god? SHOULD we play god? What of other planets that are further down the evolutionary line, and perhaps are further evolved than even our own?
I realize this relates a bit more to biology than astronomy, but it's still relative to other celestial bodies, in a way.