NASA's Goddard Conceptual Image Lab has released a video illustrating the way Mars might have looked 4 billion years ago, back when both Mars and Earth were young. It's one of the most complex scientifically informed animations the studio has ever produced, NASA says, and it is breathtaking. The music is epic-- like something you'd hear in an ancient battle movie scene--and the watery, cloudy scenery will really get your imagination going. There's even a surprise ending. Check out the video after the jump.