Bill Nye tells Hari about his Kickstarter project, the LightSail, a revolutionary solar sailing spacecraft dreamt up by Carl Sagan. How does it work? Light, says Nye, gives the spacecraft its push.

The science educator, the CEO of the Planetary Society, the “Science Guy” himself, Bill Nye joins us to talk about his new book Undeniable: Evolution and the Science of Creation and about his Kickstarter project, the LightSail, a breadbox sized spacecraft powered by the light of the sun.