The Big Question: “Why can’t everything be solar powered?” Synopsis: Harrison takes a close look at the biggest star in our solar system – the sun, and learns that everything DOES run (at least indirectly) on solar power. Without the sun, we wouldn’t… we couldn’t, even be here! My Great Challenge: Before watches were invented, people used the sun as a clock. Harrison puts two challengers to the test to see if they can tell the time the ancient way. In the Field: Harrison takes a solar-powered boat cruise with its inventor.