Which Cartoon movie is this?

I remember a cartoon movie in which an astronaut landed on a planet. The inhabitant’s society was exactly like the ours, exept that the citizens were all alien to us. The astronaunt was an alien to them and was treated as a “freak.” Is there ANYONE out there who recognizes this movie and can give me a title? I believe that it is called {Planet 51} or something similar. The movie came out in the last year or so.