answer: #Person1# tells #Person2# that Pluto is removed from the list of the planets in the solar system. They discuss the theory of geocentrism and flat earth, the possibility of interstellar travel, and the presence of aliens.
documents: #Person1#: Guess what! I know something you don't know!
  #Person2#: What's that?
  #Person1#: How many planets are there in the solar system?
  #Person2#: That's easy. Everyone knows that there are nine.
  #Person1#: Not anymore! Can you believe it? They've decided that Pluto is not a planet anymore!
  #Person2#: Nice try. I wasn't born yesterday, you know.
  #Person1#: I'm dead serious. They've decided that it's too small to be a planet, but actually they haven't yet agreed on how big something has to be in order to be a planet anymore.
  #Person2#: That sounds crazy. But they can't just change their mind about things like that.
  #Person1#: Yes, they can. If you remember correctly, people used to believe that the world was flat.
  #Person2#: I suppose you're right. They also used to think that they were so important that the sun revolved around them, not the other way around.
  #Person1#: We actually know relatively little about space and the cosmos.
  #Person2#: Do you think that we'll one day be able to travel to another planet for a vacation?
  #Person1#: I suppose we could actually live on a planet outside of the milky way.
  #Person2#: Do you think we'll ever get to meet an alien from outer space?
  #Person1#: I hope not. I think they would be a threat to those of us that lived on the Earth.
  #Person2#: You're so old-fashioned. That's what people used to think about people from another country!
  #Person1#: Point taken. Hopefully one day, we'll live in an interplanetary society.