9: The Great Gig in the Sky

The Earth of 4.5 billion years ago was perhaps the most alien version of our world, thanks to a collision with a rogue planet. Days and nights were six times shorter, the newborn Moon was as close as a weather satellite, and everything was covered with a sea of magma. Today, we learn how the Moon transformed from a giant Eye of Sauron into our pale nighttime companion, with the help of a Canadian geologist, some homemade lava, and a bucket of water. Extra credit: Squeeze a stress ball, eat only one color of candy, and try to solve this week's hidden word puzzle.