You know how when you’re looking up at the night sky, and you see that one of the stars is a little brighter than all the others, so you turn to your friend and ask, “Hey, is that a planet?” Since the chances are good that your friend is just as astronomically clueless as you are, he says, “I think so, yeah.” So you say, “Which one?” And then he says, “Jupiter probably,” but he only says that because it’s the first planet name that comes into his head. So you say, “You think?” And he says, “Maybe. Could be Mars.” Both of you stop and look up at it, and both of you wonder if you are too old to make the Uranus joke. Then he says, “I think its Mars.” And then you take a sip of your beer and curse the fact that you don’t remember anything from Astronomy class. Well, it turns out that they have that same conversation on Mars too.