For three turbulent centuries, the glimpse of a square sail and dragon-headed prow on the horizon struck terror into the hearts of medieval Europeans. Indeed, the ...

It tested the first generation of solar sail in space—a 106-square-foot sail—in 2010. Then working with The Planetary Society, it launched a slightly bigger version—the 344-square-foot ...

As the picture shows, human power was augmented by square sails rigged on masts close to the center of the longboat. This location permitted the boats to sail at an angle to the wind.

It was their magnificent longships that enabled the Vikings to set sail from their Scandinavian homelands in search of treasures and adventure. The development of the square sail at the start of ...