About How the Universe Works Season 1, Episode 6 : Planets (aka Extreme Planets)

There are just eight planets in our solar system, but there could be a hundred billion planets in our Milky Way galaxy alone. This show follows the journey of planets as they grow from grains of dust to the magnificently diverse worlds we see today. Guest Stars: Lawrence Krauss, Michio Kaku, Michelle Thaller, Phil Plait,