The world’s first solar-powered aircraft, Solar Impulse, will attempt to fly coast to coast across the U.S. The Solar Impulse is set to complete its next challenge starting in May, and by 2015 they hope to fly a similar aircraft around the world! The plane is expected to make stops at a few major airports along its journey, so the pilots can display and discuss the aircraft with reporters, students, engineers and aviation enthusiasts. The Solar Impulse has 12,000 solar cells built into its 193-foot wings to charge its batteries and allowing it to fly day and night. That’s longer than an entire Boeing 747 airplane but it weighs just 3,500 lb, less than a car. It is powered by four electric motors. The single-seat private aircraft cruises around 40 mph and can’t fly through clouds. It travels so slow that sometimes when it turns into the wind, it appears to float in place on radar screens, or occasionally even slide backward. The makers recognize that solar will never power commercial flights, but this flight was meant to push people’s assumptions about what solar technology can do.