Swiss Solar Plane Completes Overnight

After seven years of testing, tweaking, and pushing the technological envelope, Solar Impulse HB-SIA finally hit its most critical milestone to date, completing a 26-hour flight that saw the solar-powered plane fly through the night. The carbon-fiber aircraft's 200-foot wingspan is covered in 10,748 solar cells that – aside from powering the plane – store excess power in batteries that enable the plane to operate even after sunset. The all-night flight is an important proof of concept for Solar Impulse, proving solar flight is viable even when the sun doesn't shine.