You haven't? That's because you haven't explored Mars yet. Yes, that's right. I said yet.WARNING: If you're a Star Trek/sci-fi fan like myself, have tissues handy; the prospect of interplanetary travel becoming a reality might make you a little teary.
Carl Sagan recorded this message a few months before he died in 1996. In May of 2008 it was sent to Mars on a DVD with the Phoenix spacecraft for future explorers on Mars to find. It's a good thing YouTube exists to preserve and share things like this today because by the time human explorers actually get to Mars and find that DVD, DVD players probably won't even be a thing anymore.