A low-altitude flight

The wingspan of the Solar Impulse matches that of a Boeing 747, but the craft weighs only as much as a midsize car. Its array of 12,000 solar cells mounted on the wings are designed to pump renewable solar power to the plane's electric motors. Those solar cells also energize the Impulse's batteries during the day, eventually allowing it to take flight at night.

During its brief but momentous test flight, the Impulse got all of 1 meter (3.2 feet) off the ground and flew a distance of 350 meters. (By comparison, the Wright Brothers flew about 260 meters in 59 seconds in the longest flight of their first day of trying at Kitty Hawk in December 1903.)