Solar Impulse 2, a.k.a. the "Round-the-World" solar airplane, is a single-seater airplane made from carbon fiber with 17,000 solar cells that power four electric 17.5 CV (each) motors. Those solar cells also recharge the lithium batteries that allow the plane to fly at night.
The plane left on it's first journey on June 2nd, but the eventual goal is to fly all the way around the world. In the meantime, the crew is making sure there will be as few unexpected bumps in the road as possible.
The first Solar Impulse flew across the country, stopping at various cities along the way to speak with politicians, civilians, and others about the importance of alternative energy.
The Solar Impulse 2 features a 72-meter wingspan and weighs in at just 2,300 kg (about as much as a car).