Carl Sagan takes the stage at London's Royal Institution in 1977 to deliver the annual Christmas Lectures, a tradition Michael Faraday started in 1825 to get children excited about science. Across six lectures, Sagan walks a young audience through the solar system: the surface of Mars as seen by the Viking landers, the volcanic terrain of Earth, the moons of Jupiter, and the physics that governs orbits and atmospheres. He leans on models, slides, and live demonstrations rather than jargon, building each idea from something a child can see and touch before pushing into bigger questions about how planets form and whether life could exist elsewhere. The tone stays playful throughout, with Sagan pausing for audience reactions and simple experiments that make abstract mechanics concrete. Filmed only a year after the Viking missions returned their first images, the lectures carry the excitement of genuinely new data about Mars, delivered by one of the scientists closest to that data.