Early this morning at Moffet Air Field in Mountain View, California, Solar Impulse finally took off on the first leg of its barnstorming tour across the US. Of course, this isn't the first time the sun-powered plane and its pilots, Bertrand Piccard and Andre Borschberg, have flown long distance, but it is the first time it's taken wing through American airspace. Why has it come across the pond? To raise pubilc and political awareness about the benefits of going green and increasing energy efficiency -- and perhaps pick up an additional sponsor or two for its second-gen aircraft (currently in development) meant to fly around the world in 2015. "With the technologies we have onboard, we can divide by two the energy consumption of our world, and produce half of the rest [energy we need] with renewable sources" according to Piccard.