You know him from his famous science education videos, but now hear him get personal as he tells the story of how his father, while being a prisoner of war, became fascinated with sundials. Today, he has inherited the fascination, and in fact, has helped to get a sundial set up on Mars! Bill Nye, as a guest on TED Talk, teaches here what an annalemma is, and inspires viewers to learn more about our relationship to the sun.